Breakdown of the Shelf:

Normal Development	5%-10%
Immunologic Disorders	5%–10%
Diseases of the Blood and Blood-forming Organs	5%–10%
Mental Disorders	1%–5%
Diseases of the Nervous System and Special Senses	5%–10%
Cardiovascular Disorders	10%–15%
Diseases of the Respiratory System	10%–15%
Nutritional and Digestive Disorders	10%–15%
Gynecologic Disorders	1%–5%
Renal, Urinary, and Male Reproductive System	10%–15%
Disorders of Pregnancy, Childbirth, and the Puerperium	1%–5%
Disorders of the Skin and Subcutaneous Tissues	1%–5%
Diseases of the Musculoskeletal System and Connective Tissue	5%–10%
Endocrine and Metabolic Disorders	5%–10%

Immunology:

Q: A 2 year-old child comes to the urgent care clinic for a 2 days of tugging at her ears. Her father reports that she was just at the clinic a week earlier with a similar complaint. She was treated with high dose amoxicillin for that episode, which seemed to clear up after a few days. Reviewing her chart, you notice that other than two weeks ago, she was last seen for otitis media a year ago. Dad wonders if they should have her evaluated by ENT for placement of tympanostomy tubes and removal of her tonsils. Her language development is normal. Because you are an evidence-based clinician who stays current with all of the relevant clinical guidelines, you recommend what?

A:
Surgery is not yet indicated: tubes are recommended by the AAP only after 4-6 months of persistent otitis media with effusion, or after 3 months if hearing loss of >20 decibels is present. Other common guidelines recommend tubes if the patient has 3 or more AOM in 6 months, or 4 or more in a year. Tonsillectomy is never indicated for treatment of otitis media; adenoidectomy might be in older children whose OME failed to resolve with tympanostomy tubes. This patient fails to meet this criteria; she should be treated medically. While a second regiment of high dose amoxillicin could be tried, because of the rapid recurrence, a resistant bug is suspected so Augmentin (amoxicillin/clavulanic acid) would probably be best. Or this could be one of the 41% of AOM caused by a virus, so your choice of antibiotics is purely academic.

Q: An HIV+ woman comes to your office after a positive home pregnancy test. She wants to continue the pregnancy but wants to do everything possible to protect the child from becoming infected with the virus. The mother is well-controlled with HAART and has an undetectable viral load. What can be done during labor and delivery to protect the child? Is a C-section indicated once at term? What tests will confirm the presense/absense of HIV transmission to the infant?

A:
AZT should be a part of the mother’s regiment during pregnancy and labor/delivery. C-section is only indicated if the viral load is above 1,000. The baby should receive 6 weeks of oral AZT after birth. A negative HIV status is determined by two separate viral PCR studies, one at >1 month, the other at >4 months. After 6 months, the two antibody tests can be used, one month apart from each other. At age 2 months, the baby should be started on prophylaxic Bactrim, which should be given until confirmation of negative status at 6 months.

Q: At a 2 month check up, you notice that the umbilical cord is still attached. As you are reaching for the silver nitrate, you vaguely remember that this is a classic sign for what immunologic disorder? What marker protein is absent?

A:
Leukocyte Adhesion Deficiency type I (LAD I) occurs when leukocytes, macrophages and neutrophils lack CD18. This syndrome is rare … really rare: less than 200 cases are known in the US. While this patient may get you a publishable case report, it isn’t good for the infant: most die by age 2 of infection. LAD type II does not have delayed cord separation, and life expectancy is normal though patient are often developmentally delayed.

Q: In the urgent care clinic, you see a 24-month-old boy for the second time in a week. On the first visit, you diagnosed otitis media and prescribed high dose amoxicillin. This was his first ear infection. Now, five days later, he is back with the same complaint. His mother says that he never seemed to get better even though he took the medicine well. On exam, you confirm that the TMs are still inflamed and bulging. How do you treat him now?

A:
Second-line therapy for acute otitis media after failing high dose amoxicillin is typically Augmentin (amoxicillin with clavulanate to block the beta-lactamase). Other options include cefuroxime or IM ceftriaxone (Rocephin). Some experts recommend tympanocentesis for culture – but good luck ever treating the kid again after you’ve stuck a needle in his tender ear.

Q: At the end of a hot, July day, a 12-year-old boy comes to the clinic with his father. The child is complaining of left ear pain. Dad reports a history of ear infections as a child, but not many in the last couple of years. The boy reports no antecedent URI symptoms, only that his ear started hurting that morning. On physical exam, his right TM is normal. When you go to exam the left ear, the child hollers in pain when you retract his pinna. What history should you have gotten before the exam, and how do you his presumptive illness?

A:
The classic sign of otitis externa is pain with movement of the tragus and the pinna. Since this was ear pain in the summer, you should ask about swimming, especially in ponds or contaminated water. The most common cause of otitis externa is pseudomonas. Treatment is antibiotic drops, often ciprofloxacin otic.

Q: A mother bring her 5-year-old daughter to urgent care for a sore throat. She has complained that it hurts to swallow for 2 days, the mother reports. There was no antecedent illness. On exam, the oral pharynx is slightly erythematous, tonsils are enlarged but without exudate. As you begin your canned-speech about how antibiotics are useless against viral illnesses, the patient tugs on the sleeve of your white coat and says, “Doctor, look,” as she holds out her palm. It has a erythematous rash. Upon further exam, you discover a sandpaper rash on her back. “On the other hand,” you begin as you pull out your prescription pad …. What is the serious sequellae if this infection is not treated?

A:
Scarlet fever (strep throat with a rash) has a 0.3-3% chance of becoming rheumatic fever. If that happens, most patients will have polyarticular pain that is migratory. The most serious complications are carditis and valvular damage, most typically to the mitral valve. CHF can result.

Psychiatry:

Q: By what age must the symptoms of ADHD be present for the patient to have the official DSM-IV diagnosis?

A:
seven

Q: What are the major side effects of the medications commonly given to treat ADHD?

A:
Sleep and appetite impairment, increased blood pressure and pulse, exacerbation of motor tics.

Q: A parent brings a 6 year-old child in to your office for evaluation for ADHD after a difficult first year in school. The child did not do well in school, often coming home with notes from the teacher explaining that the kid was distractible and hyperactive. The child is indeed bouncing around your exam room, unable to sit still for even a moment. When the child is finally pinned down, you notice a hand tremor and tachycardia. Though you recognize the challenge of drawing blood from this child, what test should you order?

A:
Rule out hyperthyroidism: T3, T4, free T4, TSH.

Neurology:

Q: After being dropped on his head by an older sibling, little Johnny developed a seizure disorder. What is the first-line anti-epileptic medication for children?

A:
Phenytoin – it does not alter the mental status. It does have the unique property of being a drug with zero-order kinetics when metabolized by the liver.

Q: During a viral illness, a child spikes a fever. While holding the 2 year old, the care-giver notices bilaterally shaking of the extremities. The child’s eyes roll back and she become unresponsive. After a few minutes, the child stops shaking but is still lethargic. What is risk of reoccurrence of this episode with a subsequent illness, and what can be given prn to stop another attack?

A:
After a single febrile seizure, a child has a 20% risk of having a second. After the 2^nd seizure, the patient has a 50% risk of having a third. 10% of children with one febrile seizure under their belt will have more than 3. Rectal valium (Diastat) can be given to terminate a febrile seizure. Children with febrile seizures eventually grow out of them; there is no increased risk of epilepsy in children with simple febrile seizures.

Q: Concerned parents bring in their child who has been noted to stare off into space and hum from time to time. The last time it happened, the parents noticed eye fluttering. The child has no memory of these episodes. You decide to prove your neurological prowess as a physician and induce this behavior in the child right there in your exam room. What can you ask to child to do?

A:
Hyperventilate.

Q: While watching your own child competing in the local soccer league for 8-10 year olds, you notice a teammate who runs a little funny. Afterward, when her parents find out that you are a pediatrician, they ask you about this awkward gait. As it turns out, the father’s cousin – who is 30 – is in a wheelchair because of leg weakness. A “field-side” examination of the child turns up greatly diminished reflexes and loss of proprioception in the toes. To establish the diagnosis of Friedreich’s ataxia, what DNA abnormality would you look for?

A:
At least 200 repeats of the triplet GAA on chromosome 9 in the frataxin gene. The disorder requires homogenousity, thus is autosomal recessive in transmission.

Q: When reviewing the med list of a new patient, you notice that his previous pediatrician prescribed oral penicillamine. Upon opening the exam room door, you find a drooling teenager with a fixed smile and dysarthria. In addition to other physical findings, you are particularly struck by his corneas, which have green-brown rings. What heavy metal abnormality do you expect on his blood work?

A:
Low serum copper and ceruloplasmin due to Wilson’s disease. His liver function is probably also decreased due to cirrhosis caused by copper deposition. Penicillamine is a copper chelator.

Q: You see a 4-month old infant with rough, curly hair. The hair reminds you of steel wool. It’s almost … kinky. After making the presumptive diagnosis of Menkes Kinky Hair Disease, your suspicious are confirmed when you learn that the child made early milestones but seems to be regressing. The infant is hypotonic. This disorder is caused by abnormal cellular handing of what ion?

A:
Copper. (Yes, this disorder is exceedingly rare, but how could I pass up asking a question about a disorder with a name like that?)

Q: A couple newly immigrated from Europe bring their 6 month old baby for you to examine. She has been recently irritable and very sensitive to sounds. On physical exam, the baby has some spascitity with muscle weakness. On fundoscopic exam, the fovea is surrounded by a gray-white halo. A defect in what enzyme should be suspected?

A:
Hexosaminase A. This is Tay-Sachs; the gray-white halo around the fovea is the cherry-red spot.

Q: Two college-educated parents bring their 5-year-old boy to your office for evaluation after a fall. They report that he was apparently playing Superman and took a flying leap from the dresser in his bedroom. They describe him as active, even impulsive and easily distractible, and not very good at following rules. He has been on ADHD therapy for six months but without improvement. On the X-ray, there is no fracture. However, you astutely notice an area of hyperdensity in the distal metaphyseal area. Upon further questioning, you learn that the family lives in new housing in the suburbs. The mother is an artist who creates stained glass works in her studio attached to the home. The father is a history professor with a penchant for Civil War battle reenactments. How should you evaluate the child’s behavioral problems?

A:
Take a serum blood lead level. Though symptoms similar to ADHD, the bone findings are classic for chronic lead exposure. While this child didn’t get lead from the paint in his house, he is still at risk because his mother works with leaded glass and his father’s antique guns probably use lead ammunition.

Q: While examining a full term newborn in the nursery, you pull out your PanOptic ophthalmoscope to check for red reflex. Much to your surprise, the baby lacks the reflex bilaterally. What conditions should you immediately think of?

A:
Congenital cataract (most common) and retinoblastoma (most serious). Others include corneal scarring and persistence of the tunica vasculosa lentis. Retrolental fibroplasia can cause blindness in premature babies due damage to the retina caused by high arterial oxygen tensions.

Cardiovascular:

Q: In the nursery, you admit a newborn. On examination, you hear a continuous, machine-like murmur. “The baby has a patent ductus arteriosus,” you confidently tell the attending physician. “Very good,” she replies. “What is a complication of a PDA?” “Left to right shunting causing pulmonary overcirculation.” “And if it doesn’t close on its own, what medication do we give?” Because you read up on this topic the night before, you smugly reply, “Indomethicin.” “And what blood test do we run before administering Indocin, and why?” The color drains from your face. What is the answer?

A:
CBC looking for sufficient platelets. Indomethicin is a NSAID that blocks the productions of the prostaglandins that maintain the patency of the ductus. NSAIDs also block platelet function – that is why they are given to cardiac patients. You must be sure that the baby has sufficient platelets to maintain clotting after some have been decommissioned by the Indocin. Active bleeding is an absolute contraindication; renal function should also be evaluated: don’t give indomethicin to an anuric baby.

Q: You see a 8-month-old infant in your clinic for yet another infection, the third one this month. As the patient’s pediatrician, you were already aware of the baby’s cleft palate, as well as accompanying feeding difficulties that are just now being overcome. Blood chemistries show a low-normal WBC with unexpected hypocalcemia. This visit is the first time you notice that the child has slightly abnormal facial structures: the philtrum is shortened (the groove between the nose and lips). Taking into account the child’s susceptibility to infection, hypocalcemia and physical characteristics, what syndrome do you suspect, and what cardiac abnormality should you look for?

A:
DiGeorge’s is the absence of a functional thymus, leading to immunocompromise. Palatal malformation causes the cleft, the poor suck and the mid-facies abnormality. Half of DiGeorge’s patients have cardiac problems, the most common of which is interrupted aortic arch, typically between the carotid and left subclavian arteries. A large percentage will go on to have learning difficulties and/or psychoses such as paranoid schizophrenia.

Q: Early in the morning, you are called to the nursery to evaluate a cyanotic newborn. On cardiac exam, the baby has a systolic murmur over the left lower sternal border with extra heart sounds. After transferring the infant to the NICU and while waiting for the echo, you have a chance to review the patient’s chart and prenatal history. It’s a thin chart because the mother did not receive much prenatal care. The mother’s chart, on the other hand, is quite thick – filled with admissions to the psychiatry service. The echo report indicates tricuspid regurgitation secondary to valve malformation, as well as a ASD. The right atrium is quite large. What medication do you suspect the mother was taking during pregnancy?

A:
Ebstein’s anomaly is a malformation of the tricuspid valve causing some of the leaflets to be in the ventricle, leading to regurg and atrial dilatation. It is associated with lithium, which is prescribed as a mood stabilizer for bipolar disease.

Q: What cyanotic disease of infancy is the only one in which PGE₁ is contraindicated?

A:
Total anomalous pulmonary venous return (TAPVR). The blood returning from the lungs is dumped into the vena cava, the coronary sinus or straight into the right atrium. The ductus arteriosus increases the blood flow into the already overwhelmed right atrium, so it should be allowed to close. Surgical correction of the major vessels is needed in the first month of life.

Q: An 18-month-old child comes to urgent care with a history of fever for several days. The child has an erythematous rash on his trunk. There is also an erythematous rash on his hands and feet, which are also swollen. Conjunctivitis is present bilaterally without purulence. The child’s lips are cracked and there is a single palpable cervical lymph node. The strawberry tongue confirms to you that this is Kawasaki’s disease. What treatment should be started, and what serious sequella is it intended to prevent?

A:
Coronary aneurysm is the bad thing that IVIG therapy prevents. High dose aspirin can also be given, but steroids are contraindicated due to their association with aneurysm formation. The aneurysm typically forms 11-30 days after the fever, so there is still time to treat.

Respiratory:

Q: A man in his twenties comes to your clinic for a regular check-up. You’ve seen him for several years for recurrent lung infections, chronic sinusitis and even a few cases of otitis media as an adult. Each time you got to listen to his chest, he reminds you that he’s “a staunch conservative – even my heart is located on the right.” Today, his lungs are clear, but the multiple courses of pulmonary infection have caused him to have bronchiectasis. At the end of the visit, he impedes your exit with a serious question: “Doc, I’ve met a wonderful woman. But before I commit to her, I have to know: what are the chances that my children will have the same problems that I have?” What do you say to him?

A:
Assuming you have a solid doctor-patient relationship, you might start with, “I have good news and bad news. The good news is that you won’t pass this disease on to you kids. The bad news? You won’t be having kids.” This patient has Kartagener syndrome, a defect in the dynein arms that causes cilia dysfunction. Since sperm are essentially balls of DNA with a cilia tail, male infertility is universal. However, in vitro fertilization is possible – in which case your patient should know that Kartagener is autosomal recessive, so his kids will definitely be carriers.

Q: A 3 month-old infant presents with stridor. The baby has no history of URI or other infection. She is up to date on her immunizations and has no sick contacts. The parents deny the possibility of inhaled foreign body. Her examination is benign except for the stridor, a cerulean spot on her thigh and a hemangioma on her chin. On X-ray, the lateral film is normal; the AP shows some asymmetric stenosis of the subglottis. What do you suspect is the cause of her breathing difficulties?

A:
A laryngeal hemangioma. More than half of laryngeal hemangiomas are associated with facial hemangiomas (the cerulean spot was thrown in as a red herring). While the hemangioma will regress (as will the one on her chin), the patient may require a tracheotomy before that happens. Other treatment options include laser surgery and steroids.

Gastrointestinal and Nutrition:

Q: A 13 year old girl with a 7 year history of insulin dependent diabetes mellitus is seen for a follow up visit after a hospitalization for DKA. Her hemoglobin A1c is 14. On physical exam, her liver is noted to be enlarged. Subsequent liver function test enzymes are found to be greatly elevated. What’s up with that liver? Do you suspect the patient is consuming too many carbohydrates in the form of brewed beverages?

A:
No, this is Mauriac’s syndrome: hepatomegaly due to glycogen-deposition in a poorly controlled diabetic. With better glucose control, the liver will return to normal. Other feature of Mauriac’s include moon face, protuberant abdomen, and proximal muscle wasting.

Q: A 10-year-old African-American boy comes to your clinic complaining of “borborygmus.” After you excuse yourself from the room for a minute to look up that word in your medical dictionary (“the rumbling noise of gas moving through the small intestine”), you continue taking the history: he has this problem after eating dairy products. Loose, watery diarrhea often accompanies the bloating. Aside from empirical elimination of lactose products from his diet, what test could you order to prove the diagnosis?

A:
Hydrogen breath test is the easiest. You could also test his stool for unabsorbed carbohydrates, but that’s a little messy. Another option is a fasting lactose challenge, looking for an increase in blood sugar – failure to increase indicates a lack of lactase enzyme to break the lactose up into absorbable glucose and galactose. However, testing only facilitates your revenge for being one-upped by the boy’s vocabulary: 90% African-Americans are lactose intolerant, as are 90% of Asians. About 70% of Hispanics are, while a mere 5% of Northern Europeans lack the enzyme … they are the mutants.

Q: At 3am, you are called to the ED to evaluate a 4-year-old with diarrhea. Glancing at her labs on your way to see her, you notice that she is anemic and thrombocytopenic with some electrolyte imbalances. Upon seeing her, you note that she is ill-appearing with petechiae on her arms. She has had several days of watery stools, some streaked with blood. Her problems started a day after she attended a friend’s birthday party at a local Jack-in-the-Box. What bug and/or toxin do you suspect? What organ system are you most worried about?

A:
She has hemolytic uremic syndrome (HUS) from Shiga toxin produced by E. coli 0157;H7. Your major concern should be her renal function – the toxin binds to a glycolipid receptor molecule in the glomeroli causing the release of platelet-activating substances. Platelets accumulate in the kidneys causing the thrombocytopenia; RBCs are shredded while they traverse the glomeroli causing the hemolytic anemia.

Q: A mother brings her 6-month-old boy to see you. He had had diarrhea for a couple of days, with one episode of vomiting. No one in the home is sick, and the mother is concerned that the baby isn’t tolerating his formula. She recently switched from breast feeding to bottle to facilitate her return to work. What test do you order to evaluate for possible milk-protein allergy?

A:
Radioallergosorbent test (RAST) will look for IgE to various antigen in the infant’s system looking for milk protein allergy. A non-radioactive alternative is ELISA but it is less reliable.

Q: 85% of infants vomit in the first week of life. Not all are medically treated, but many are given metoclopramide (Reglan). What is its mechanism of action?

A:
Antagonizes central and peripheral dopamine receptors. Central receptors in the chemoreceptor trigger zone of the medulla respond to dopamine by making the patient feel nauseous and vomit. By blocking peripheral dopamine receptors, stomach motility and contractions are improved.

Q: According to Essentials of Nelson’s, “In the near future, rotavirus diarrhea may be prevented by vaccination.” In fact, there was a vaccine for rotavirus, but it was pulled from the market after being associated with what condition that classically presents itself with a currant jelly stool and sausage-like mass in the abdomen of an infant?

A:
Intussusception. CDC data showed that the vaccination was associated with a 20-30 times increased risk of intussusception over what would be expected in the population. This is an example of how the Vaccine Adverse Event Reporting System (VAERS) is used to ensure the safety of vaccines.

Q: A mother brings her newborn baby to your clinic with the complaint that the infant is saving her money by not soiling diapers … he hasn’t had a bowel movement. Ever. What is your differential diagnosis for failure to produce meconium?

A:
While cystic fibrosis may be the first thing to come to mind, 90% of CF kids produce meconium (which is quite thick and sticky). Causes of complete failure to defecate include the other 10% of CF patients, Hirschsprung’s (aganglionic colon), spinal cord defects, and imperforate anus (or, as one mother put it, “My baby ain’t got no booty hole.”).

Q: Two infants are born with their intestines outside of their bellies. In one, the small bowel is covered by thin sac. In the other, the small bowel exits the belly just to the right of the umbilicus and is exposed to the air. It has a thickened, leathery appearance. Which infant requires further work up to rule out other congenital defects, and what disorders are you looking for?

A:
Omphalocele results when the gut fails to return to the body after its exploration of the amniotic nether-regions (when it rotates 270 degrees). The bowel is covered by the peritoneum and amniotic membranes. Omphalocele is associated with other birth defects, such as other GI malformations, heart defects and Beckwith-Wiedermann (exophthalmos, macroglossia, gigantism, hyperinsulinemia, hypoglycemia). Gastroschisis is caused by a physical defect in the abdominal wall, usually to the right of the umbilical cord. It requires surgical correction, possibly including the resection of the extruding small bowel.

Q: IgA endomysial antibodies are specific for what disease?

A:
Gluten-sensitivity (celiac disease). It typically presents at age 6-18 months when the child is first introduced to grain-based foods such as cereals. Symptoms are vague: apathy, irritability, pain, vomiting, abdominal distension, failure to thrive. More severe cases have skeletal muscle wasting, finger clubbing and peripheral edema. Diagnosis is made by changes seen on small bowel biopsy after implementing a gluten-free diet. Other serum tests include IgG or IgA against gliadin and reticulin.

Renal and Reproductive:

Q: A couple brings their 7-day-old infant to your office for his first exam. He was a full-term normal vaginal birth … if by “normal” you mean “on the kitchen floor, attended by a midwife and the child’s doting grandparents.” Because this is the child’s first encounter with a physician, you provide a full examination. On exam, you notice that the boy’s genitilia are small: his penis is 2.5 cm long when stretched (normal is 3.5 cm). The scrotal sac is present, as are very small testes. What do you tell the parents?

a) Your child has micropenis – it’s hereditary.

b) Your child’s best option would be to make that “pole” into a “hole” – gender reassignment

c) After ruling out chromosomal abnormalities, this condition can be successfully treated with 1-3 doses of testosterone

A:
(c) is obviously the correct answer. Microphallus is caused by decreased testosterone in utero, usually as a result of gonadotropin deficiency. Other things to be considered are Pradi-Willi, Kallman’s (lack of smell, in addition, but hard to ask a newborn if they smell the coffee), Klinefelter’s, androgen insensitivity and 5-alpha reductase deficiency.

Q: An anxious parent brings her 8-year-old son to your clinic because he (and she) is embarrassed by his bedwetting. He wets the bed three or four times a week and has done so since being toilet trained at age 3. The mother thought he would grow out of it, but is now frustrated that he still continues. He is becoming socially withdrawn because he can’t participate in sleep-overs at his friend’s house without the risk of becoming known as “pee-pee Peter.” Since you want to cure him, and they are will to try anything, what therapy should you offer?

A:
Conditioning therapy that consists of underwear wired to an alarm to awaken the child. This treatment is the most effective, working 30-60% of the time and is most effective in older children. Medications, such as imipramine or DDAVP, can also be tried, but have a higher failure rate.

Q: The next parent brings his son in because his kindergarten teacher mentioned that he asks to go to the bathroom every 20 minutes. When you ask the child, he says that empties his bladder each time, but then just has to go again. He never wets himself or the bed at night. Further history makes you rule out diabetes, and the child has no complaints of dysuria. The father, off hand, mentions that he and his wife are currently separated. What do you tell dad?

A:
This is likely pollakiuria – repetitive voiding by a 4-6 year-old child, often during times of stress, and almost always boys. The condition typically resolves on its own.

Q: A 16-year-old girl comes to your adolescent clinic for a yearly check up. At the previous visit, she started oral contraceptive pills because she was sexually active with her 17-year-old boyfriend. During the history, she reports having broken up with that “loser” and having several different partners over ensuing year. She has had no problems with the OCP, and has never missed a dose. However over the past couple of weeks, she has noted dysparinia. What are the major and minor criteria to establish a diagnosis of PID?

A:
Major criteria are cervical motion tenderness, abdominal pain on palpation and adnexal tenderness. Minor criteria are oral temperature greater than 101 F (greater than 38.3 C), abnormal cervical or vaginal discharge, elevated erythrocyte sedimentation rate, elevated C-reactive protein, and laboratory documentation of cervical infection with N. gonorrhoeae or C. trachomatis. Only one major and one minor criteria is needed to justify treatment with levofloxacin and metronidazole for 2 weeks.

Q: You see a 6-year-old girl who complains of urinary frequency with burning. She’s never had this before, but her mother recognized these as symptoms of a urinary tract infection and so brought the daughter to see you. The nurse already obtained a urine sample and sent it to the lab. Because you were running terribly behind that day, the U/A results were back before you saw the patient: positive for E. coli. What is the next step for this patient? What if the patient were a 6-year-old boy?

A:
Treat for the UTI. If a boy presents with these symptoms, a voiding cystourethragram (VCUG) is indicated because boys don’t get UTIs unless they have abnormal anatomy. VCUG is indicated in girls <2 years or if multiple infections.

Musculoskeletal and Connective Tissue:

Q: An infant presents with the symptoms of spinal muscular atrophy, type I: floppy and unable to sit without support. A family history turns up the expected autosomal recessive transmission pattern. What would be the results of an EMG on this patient?

A:
Spinal muscular atrophy has a wide range of variant that are beyond the scope of this answer. Type I presents by 6 months of age with the symptoms described above. The lesion is a deterioration of the anterior horn cells of the spinal cord at all levels. An EMG will show normal conduction in sensory nerves, a loss of motor unit action potentials and a loss of motor nerve conduction.

Endocrine and Metabolic:

Q: Propylthiouracil is used to treat what condition?

A:
Hyperthyroid, including Grave’s disease. About half of all Grave’s disease will remit on its own, so PTU can be given in the interim (12-24 months).

Q: “Congratulations! It’s a baby b-, err, gi- … um … it’s a baby!” Sex assignment can be difficult in congenital adrenal hyperplasia because of ambiguous genitalia. What enzyme is deficient in 90% of CAH, and which gender has its key external features distorted?

A:
21-hydroxylase deficiency is found in 90% of CAH (11-hydrolylase deficiency is found in another 5%). The adrenals are unable to produce cortisol, but the pituitaries sense this problem and crank out more ACTH in an attempt to normalize the cortisol levels. Unfortunately, this causes excess androgens to be produced as the chemical intermediates of cortisol get shunted to that pathway, thus girls come out with cliteromegaly and labioscrotal fusion. Boys are phenotypically normal but will have salt wasting and dehydration like the girls, but are harder to identify because of their normal genitalia.