A rapidly deteriorating baby girl: Can you judge this book by its cover?

You've been called to the emergency department of your hospital to evaluate a 6-month-old Amish girl transferred from another hospital with a five-day history of vomiting and three days of cough, increasing somnolence, weak suck, decreased appetite, decreased output of urine, and pallor. You turn first to the chart for background on this clearly ill baby.

The record shows one episode of postprandial vomiting on the first day of her illness; on the second day, she began vomiting after almost every feeding. The parents reported that the vomitus "looked like milk," contained neither blood nor bile, and was non-projectile.

Over the next three days, the baby's vomiting diminished slightly-as did her appetite. Her parents gave her cod liver oil but no other medications or supplements.

Small at first, then smaller The patient was born at term by vaginal delivery, at home, weighing 2,950 g (6 lbs, 8 oz)-approximately the 20th percentile. At 2 weeks, weight had dropped to below the 5thpercentile. Although she has remained slightly below that 5th percentile for weight, growth has followed the curve well for weight, length, and head circumference. Both parents are at the 5th percentile for adult height.

According to her mother, the baby breastfed well until she was 2 months old; then, the mother developed a monilial breast infection and weaned her. She was then started on a 1:2 mixture of canned cream (i.e., the top layer skimmed from cow milk) to boiled water with "some" sugar added-a common practice in the Amish community in which the family lives, the mother reports. The baby's only other nutrition is tea with brown sugar and occasional cod liver oil, dosage unknown. Continued satisfactory weight gain was confirmed at her last weight check, two weeks ago.

The parents report no other illnesses or hospitalizations. The patient has met all developmental milestones. She is the 12th child born to her parents, with 10 siblings alive; the family's first child died at 6 weeks of age of "crib death." One sibling has a seizure disorder; the others, and the parents, are healthy. The parents may be distantly related, they acknowledge.

A review of systems is positive for diaper rash, which the baby develops "occasionally," according to the mother. On examination, rectal temperature is 102.8° F; pulse, 160; respirations, 40/min; and blood pressure, 92/61 mm Hg. Weight is 5.3 kg; height, 60 cm; and head circumference, 39.5 cm-all, as anticipated, below the 5th percentile.

The girl is alert but appears tired. Mucous membranes are dry. She appears appropriately proportional and well nourished; she is not dysmorphic. HEENT, respiratory, and cardiovascular examinations are negative except for the heart rate, which varies from 140 to 180/min. The abdomen is distended but soft, without organomegaly. She has normal tone, reflexes, and strength. Skin is pink, cool, and free of rash other than in the diaper area.

You construct a differential diagnosis for vomiting with fever. It includes:

You request that blood be drawn for electrolyte and liver function testing (LFTs) and a CBC, and proceed with a work-up to rule out sepsis and meningitis. Because the patient appears dehydrated, the ED physician has administered a 20 mL/kg IV bolus of normal saline.

It's pleasing to see your patient perk up once the fluid is in. Test results return: sodium, 156 mEql/L; potassium, 3.3 mEql/L; chloride, 123 mEql/L; bicarbonate, 12 mEql/L; blood urea nitrogen (BUN), 41 mg/dL; creatinine, 1.2 mg/dL; and glucose, 269 mg/dL.