Case 335 -- Elevated Ammonia Levels

Contributed by Kudakwashe Chikwava, MD, David N Finegold, MD
Published on line in January 2003


PATIENT HISTORY:

CHIEF COMPLAINTS: The patient is a 15-year-old male with history of hypercholesterolemia, who was transferred from an outside hospital after he presented with a five-day history of low-grade temperature, nausea, and vomiting. He had been seen by his PCP 3 days prior and was referred to the outside hospital where he was given IV fluids, and was subsequently discharged on promethazine (pr). However, the symptoms did not improve, and he developed and ataxia and slurred speech, for which he returned to the outside hospital. On the second admission he had a head CT scan, which was negative and normal CBC, electrolytes and liver function tests. Subsequently the patient was transferred to Children's Hospital of Pittsburgh for further work up and management. A review of the all other systems was unremarkable.

CURRENT MEDICATIONS: None.

ALLERGIES: Denies known medication allergies.

FAMILY HISTORY: Positive for the patient's father and sister who have hypercholesterolemia.

PHYSICAL EXAMINATION:

APPEARANCE: Well-developed. Lethargic, drowsy and stuporous. Glasgow Coma Scale: Total Score = 13. The skin revealed no rashes, no petechiae or purpura.

VITAL SIGNS: BP: 134/75. T: 36.6 P: 68 regular. R: 20.

HEAD, EYES, EARS, NOSE AND THROAT: Normal with pupils 3 to 4mm and equally reactive to light.

NEUROLOGIC:
Motor: The neck was supple and non-tender. Strength was 4/5 at hip and shoulder girdle.
Sensory: Loss of sense of light touch of left knee, shin and foot. Loss of sense of proprioception of left forearm, knee, shin and foot. The remainder of the neurological and other sytems was normal.

INITIAL (ER) DIAGNOSIS:

  1. Encephalopathy - unknown cause.
  2. Altered mental status/ RO seizures.

INITIAL HOSPITAL COURSE:

Neurologists were consulted and they noted fluctuating level of consciousness and ordered a Stat urine toxicology screen, EEG and also wanted an LP for viral meningitis and metabolic screen.

Urine tox screen, CBC, Electrolytes, LFTs and UA were negative (Table 1) and EEG showed a diffuse slow (4Hz) and triphasic wave pattern suggestive of metabolic disorder. Ammonia level was sent, for which he was high, level of 267 umol/L.

    TABLE 1. INITIAL LABORATORY RESULTS

      Analyte   Result   Normal range
      Urine comprehensive drug screen   Positive for promethazine only   NDA ( Note that patient was on pr phenergan from outside hospital)
      Serum toxicology screen   Negative for THC, TCAs, PCP, amphetamines, barbiturates, benzodiazepines, cocaine, alcohol and opiates   NDA
      Glucose   99 mg/dL   70-110 mg/dL
      Potassium   4.2 mEq/L   3.5-5.0 mEq/L
      Chloride   104 mEq/L   95-110 mEq/L
      Co2   23 mEq/L   21.0-31.0 mEq/L
      Blood Urea Nitrogen   15 mg/dL   5-20 mg/dL
      Creatinine   0.8 mg/dL   0.5-1.4 mg/dL
      Hemoglobin   16 g/dL   13.5-17.5 g/dL
      Hematocrit   50%   37-49%
      White Cell Count   5.3 x 10E+09/L   4.5-13 x 10E+09/L
      Platelets   201 x 10E+09/L   156-369 x 10E+09/L
      Alkaline Phosphate   164 IU/L   40-125 IU/L
      Aspatate aminotransferase (AST)   25 IU/L   <40 IU/L
      Alanine aminotransferase (ALT)   50 IU/L   <40 IU/L
      Cholesterol   234 mg/dL   135-168 mg/dL
      Triglyceride   39 mg/dL   53-88 mg/dL

The patient was then transferred to PICU for further management were an infusion with sodium phenylbutyrate, citrulline, as well as arginine was commenced at approximately 12 hours post admission. The resulting precipitous resolution of the elevated ammonia levels is shown in Figure 1.

While in PICU urine orotic acid was 62.6 ug/mg Creat. Most of the urine amino acids were normal with occasional only slightly elevated measurements. Serum amino acids were within normal range.

FINAL DIAGNOSIS


Case IndexCME Case StudiesFeedbackHome