Diagnosis of Absorption Disorders
Absorption disorder diagnosis varies, depending on the underlying cause for the condition. A personal and family medical history, physical examination, and laboratory tests (e.g., blood tests, stool tests) may be used to make a diagnosis.
A medical history includes information about the patient's history of symptoms (e.g., symptom onset, severity, factors that worsen or improve symptoms), diet, and family history of malabsorption syndromes or related conditions (e.g., genetic disorders, autoimmune disorders).
Laboratory tests that may be used to diagnose absorption disorders include the following:
- Blood tests (e.g., complete blood count [CBC], total serum protein, cholesterol tests, liver function tests)
- Stool tests (used to measure pH levels and detect abnormal levels of certain substances, such as fats, proteins, bacteria, and parasites)
- Urinalysis (used to detect high levels of malabsorbed nutrients)
Additional blood tests that may be performed include erythrocyte sedimentation rate (ESR or sed rate) and C-reactive protein level. ESR measures how quickly mature red blood cells (called erythrocytes or corpuscles) fall to the bottom of a test tube, indicating the level of inflammation that is present in the body. High levels of C-reactive protein, which is a marker in the blood, also can indicate inflammation.
Other diagnostic tests include substance tolerance tests and biopsy of the intestinal lining. In substance tolerance tests, the suspected nutrient is removed from the diet for a period of time. If symptoms subside and then resume after the nutrient is re-introduced, malabsorption of the specific nutrient may be indicated.
Biopsy of the lining of the small intestine (mucosa) involves surgical removal of a small tissue sample for microscopic evaluation. Biopsy may reveal damage (e.g., lesions, ulcers) in the GI tract.