electrolyte or glucose derangement may be the cause of

abdominal pain, as seen in hypercalcemia and diabetic

ketoacidosis.

Blood urea nitrogen and creatinine. Renal function

tests should be obtained in patients for whom there is concern for dehydration or severe sepsis. They are also necessary before intravenous contrast is given for a computed

tomography (CT) scan to prevent patients with renal

insufficiency incurring contrast nephropathy.

Urinalysis. A urinary tract infection (UTI) is suggested by the presence of leukocyte esterase, nitrates,

pyuria, and bacteria. Careful interpretation of this test is

necessary, as inflammatory processes ( eg, appendicitis,

diverticulitis) near the ureter may produce pyuria in the

absence of a UTI.

ACUTE ABDOMINAL PAIN

Pregnancy test. All females of childbearing age should

be tested for pregnancy. This is routinely accomplished

through qualitative testing of the urine. If positive, this is

followed by a quantitative serum beta human chorionic

gonadotropin level in conjunction with pelvic ultrasound

to exclude an ectopic pregnancy.

Liver function tests (LFTs). LFT abnormalities can be

seen in both hepatic and biliary tract disorders. A hepatic

picture involves increases in aspartate aminotransferase (AST)

and alanine aminotransferase (ALT) greater than alkaline

phosphatase (ALP). An obstructive (cholestatic) picture is

seen when the increase in ALP is greater than that of AST/

ALT, along with the presence of hyperbilirubinemia.

Marked transaminitis (> 1 ,000 IU/L) is typically only seen

in toxin/drug-induced hepatitis, acute viral hepatitis, or

ischemic hepatitis (shock liver).

Lipase. A value 2 times normal is 94% sensitive and

95% specific for pancreatitis. An elevated lipase in conjunction with cholestatic LFT abnormalities should raise

concern for gallstone pancreatitis.

Coagulation tests. Patients on warfarin should have

their international normalized ratio checked for both diagnostic and treatment purposes. Being subtherapeutic in

the setting of atrial fibrillation could raise concern for

mesenteric ischemia. Supra-therapeutic levels can raise

suspicion for hemorrhagic diseases such as a rectus sheath

hematoma.