A 22 year old man is brought to the ER with abdominal pain.
It is severe and he has had several such episodes in the past. The pain is central
abdominal pain of a dull aching quality. his mother is with him and says that he has been
behaving odd today. He had his last bowel movement today and there was no blood. He denies
any rashes or photosensitivity. He says he does not trust his primary care doctor because
he keeps sending him to different doctors who have done multiple tests on him and have not
come up with any diagnosis.
You perform an extensive examination and besides vague abdominal tenderness are not able
to elicit any specific findings. He is afebrile and normotensive. Rectal exam shows
normal stool and guiac test is negative.
He has had a CT scan of his abdomen, Spine and pelvis. He underwent an angiogram for his
mesenteric vessels which was normal. His CBC shows WBC count of 15,000, platelets of
168,000 and Hb. 14. His Liver function tests are normal. Serum chemistry shows Na 129, K
4.0, Cl 95, HCO3 23, BUN 18 and Cr. 1.0 & Glucose 103mg%. Amylase and lipase are
normal. His EKG shows no ischemia but he has a heart rate of 118.
Q1. What is the correct diagnosis for this patient?
Fill in the blank _______________________________
Answer was acute intermittent porphyria.
Objective is to know when to suspect unusual
diseases. In the case of abdominal pain, start suspecting these as soon as imaging and
stool guiac test are normal.
In this case with abdominal pain, there are a few possibilities. One must take into
account that the patient has an altered mental status inspite of almost normal
electrolytes. He also has hyponatremia. Then there is tachycardia
and normal BP and normal Glucose and creatinine.
The differential includes
Addison's disease, DKA, Black widow spider bite, Abdominal epilepsy, mesenteric ischemia
and Acute intermittent porphyria.
Let us tease out each one and see if it fits into this patient's picture.
Differential Diagnosis | Features of the differential diagnosis present in this case | Features of the differential diagnosis absent in this case | Likelihood of the diagnosis in this case |
Addison's crisis | Abdominal pain, hyponatremia | Hyperkalemia, hypotension, Metabolic acidosis, elevated BUN | Fair |
DKA (diabetic Keto-acidosis) | Young patient, abdominal pain | Low HCO3, hyperglycemia, no resolution without treatment | Unlikely |
Black widow spider bite | Abdominal pain | Not recurrent, Mental status normal, rigid abdomen | Unlikely |
Hereditary angio-edema (C1 esterase deficiency) | Abdominal pain | Rash, hereditary, family history | Fair |
Abdominal epilepsy | Abdominal pain | Rare, abdominal rigidity | Unlikely |
Irritable bowel syndrome | Almost normal labs & imaging | Tachycardia, altered mental status, hyponatremia | |
Acute intermittent porphyria | Abdominal pain, hyponatremia, altered mental status, normal routine labs, Tachycardia | High Fulfils the major problems in the case and is the diagnosis |