The Molecular Basis of Medicine



The Molecular Basis of Medicine

Step 1

Case4

Sophie Claiborne's Upset Stomach

Step Master: W. Marshall Anderson, Ph.D.

Tutors: W. Marshall Anderson, Ph.D.

Mary Ann Kirkish, Ph.D.

Susanna Alverez- Banks, Ph.D.

Case Author: W. Marshall Anderson, Ph.D. and Mary Ann Kirkish, Ph.D.

Case Editors: Case Review Committee.

The Molecular Basis of Medicine

Step 1

Case 4 First Session

Sophie Claiborne, a 3-month-old female infant (birth date November 17, 1985), is brought to her pediatrician by her mother. Mrs. Claiborne tells Dr. Welmann that Sophie has had bouts of inconsolable crying, vomiting, and has not been gaining weight. The bouts of crying and vomiting seem to be brought on by feeding. Dr. Welmann performs a quick exam and finds Sophie’s vitals to be within normal limits (WNL). She tells Mrs. Claiborne that Sophie may have a milk allergy. She switches Sophie from breast milk to a proprietary formula lacking lactose.

4-1

The Molecular Basis of Medicine

Step 1

Case 4 First Session continued

Sophie's bouts of crying and vomiting subside over the next several months, but at 8 months she is still below the norm in weight gain and develops a skin rash. Dr. Welmann switches Sophie to a soy protein formula.

(Give out growth chart if students do not already have one). (Growth charts are also available online at National Center for Health Statistics – Clinical Growth Charts retrieved March 12, 2007

4-2

The Molecular Basis of Medicine

Step 1

Case 4 First Session continued

At 35 months Sophie begins to have further problems and is brought back to see Dr. Welmann. Mrs. Claiborne reminds Dr. Welmann that Sophie has been having problems since weaning from the soy protein formula. Sophie has always been irritable and hyperactive, but recently has been ill and vomited after eating either meat or cheese. She became very inactive after each bout of vomiting. This morning she was having problems with words (like a stutter) and also was very uncoordinated and having trouble walking. Mrs. Claiborne is very concerned about Sophie.

Dr. Welmann checks Sophie's vitals, which are within normal limits and performed a quick physical. She noted that Sophie was alert but irritable. Physical exam was unremarkable as was neurological exam.

Dr. Welmann had her assistant take some blood from Sophie for a complete blood count (CBC) and a complete metabolic panel (CMP). Sophie began to cry and was inconsolable for almost a half hour.

Pertinent results from Sophie Claiborne's blood chemistry:

Analyte Patient Reference values

AST* 59 U/L 5-40 U/L

ALT 88 U/L 7-56 U/L

BUN 2 mg/dL 5 -18 mg/dL

pH 7.44 7.34-7.44

Based on the preliminary results, Dr. Welmann ordered an ammonia level on Sophie.

Dr. Welmann told Mrs. Claiborne to take Sophie home and try to keep Sophie calm and refrain from feeding her either meat or cheese.

*AST – aspartate aninotransferase; ALT – alanine aminotransferase; BUN – blood urea nitrogen

4-3

The Molecular Basis of Medicine

Step 1

Case 4 First Session continued

The next day, Dr. Welmann called Sophie’s mother and asked Mrs. Claiborne to come into the office to discuss Sophie’s test results.

Analyte Patient Reference values

Ammonia 51 µM 11-32 µM

Sophie’s ammonia level was high and Dr. Welmann advises Mrs. Claiborne to restrict Sophie's protein intake. Dr. Welmann recommends a consult with a dietician so Mrs. Claiborne can learn how to properly restrict protein intake while still providing adequate nutrition for Sophie.

4-4

The Molecular Basis of Medicine

Step 1

Case 4 Second Session

Sophie improves somewhat on the restricted protein diet. At age 43 months she finds some cheese left on the kitchen table by her older brother (7 years old) and eats it. Her mother finds her unresponsive on the kitchen floor and rushes her to the emergency room.

Sophie arrives in the ER in a comatose condition. The order is given to draw arterial blood gases (ABG), a STAT blood glucose and to insert an IV line. Stat blood glucose is within normal limits but blood pH is high (7.47). More blood is drawn for further tests and Sophie is given more normal saline (to lower blood pH). Pertinent values from Sophie's blood test:

Analyte Patient Reference values

AST 83 U/L 5-40 U/L

ALT 167 U/L 7-56 U/L

Ammonia 216 µM 11-32 µM

BUN 5 mM 2.5-6.4 mM

PCO2 28 mm Hg 35-45 mm Hg

Sophie is admitted to the hospital. She gradually improves and becomes conscious with hydration and protein restriction. Further blood tests are ordered.

4-5

The Molecular Basis of Medicine

Step 1

Case 4

Second Session Continued

Quantitative plasma amino acid analysis results on Sophie Claiborne showed:

Analyte Patient Reference Value

Plasma glutamine 2146 µM 420-730 µM

Plasma citrulline 20 µM 16-32 µM

Plasma alanine 281 µM 200-450 µM

Plasma arginine 46 µM 44-120 µM

To further define Sophie’s problem, urinary orotic acid excretion is determined.

Analyte Patient Reference Value

Urinary orotic acid* 379 µg ................
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