Malabsorption

Testing

The purpose of testing may be to:

• Screen those at risk for malabsorption because of an underlying condition such as cystic fibrosis
• Detect malabsorption, identify its underlying cause(s), and evaluate the types and severity of nutrient deficiencies present
• Detect complications such as anemia
• Monitor the effectiveness of treatment in people with malabsorption

There is no single test that can identify malabsorption or the underlying cause. Typically, a doctor will take into account many factors when ordering tests, including results from a physical examination, family history, medical history, and signs and symptoms. Testing will often be performed in steps with results leading toward a diagnosis while ruling out other possible causes. Testing typically involves ordering:

• An initial set of general tests that evaluate body organs, cells, and digestion and that look for a cause for a person's persistent diarrhea, one of the most common symptoms of malabsorption
• Specific follow-up tests that are used to detect or exclude diseases associated with malabsorption and to identify specific deficiencies and/or complications

Laboratory Tests

Initial testing may include:

• Complete blood count (CBC) – to evaluate red blood cells to detect anemia and white blood cells to detect infections
• Comprehensive metabolic panel (CMP) – to evaluate proteins, electrolytes, and organ function, including the liver
• Prealbumin – this is used as a marker for protein malabsorption and indicates general nutritional status
• Erythrocyte sedimentation rate (ESR) – to detect inflammation in the body which may be caused, for example, by inflammatory bowel syndrome
• Fecal fat – to detect decreased ability to digest fat
• Stool culture – to detect bacterial infection or bacterial overgrowth as cause of persistent diarrhea
• Ova and parasite examination (O&P) – to detect parasites as cause of persistent diarrhea
• Stool white blood cells – present in some inflammatory intestinal diseases
• Thyroid stimulating hormone (TSH) – to detect or rule out thyroid disease

Based upon initial testing results, the person's symptoms, and the doctor's suspicions, follow-up testing may include one or more of the following:

• Fecal occult blood test – to detect bleeding in the digestive tract
• Levels of vitamin B12, vitamin D, vitamin A – to detect deficiency
• Prothrombin time (PT) – to detect vitamin K deficiency
• Celiac disease tests – to help diagnose this condition
• Cystic fibrosis tests – to detect this disease
• Fecal elastase, trypsin, trypsinogen, amylase, lipase – to evaluate pancreatic function

Tests sometimes ordered include:

• Methylmalonic Acid (MMA) – to detect early vitamin B12 deficiency
• Hydrogen breath test – to detect lactose intolerance and bacterial overgrowth in the digestive system (carbohydrate malabsorption)
• Xylose absorption test – to evaluate carbohydrate digestion
• Lactose absorption test – though this test is primarily used to detect a deficiency in the enzyme lactase (lactose intolerance), it may sometimes be used to identify malabsorption
• Biopsy of the intestine

Non-Laboratory Tests

Testing to examine the digestive tract, liver, and/or pancreas is sometimes necessary and may include:

• Abdominal ultrasound
• CT scan
• Endoscopy
• Endoscopic retrograde pancreatography (ERCP)

Learn more about these imaging procedures at Radiologyinfo.org.