Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (924 page)

   Pancreatitis

Decreased In

   NA

   Limitations

   For a 72-hour stool collection, 50–150 g of fat a day for 2–3 days prior to and during the stool collection period needs to be consumed. The fat should be long-chain triglycerides (such as corn or olive oil, not butter).

   False-positive results can occur due to mineral oil or castor oil present in the specimen.

FERRITIN

   Definition

   Ferritin is the cellular storage protein for iron, with 1 ng of ferritin per mL indicating 10 mg of total iron stores. It is a huge (440 kDa), 24-subunit protein consisting of light and heavy chains, which can store up to 4,500 atoms of iron. Ferritin is an acute-phase reactant, and, along with transferrin and its receptor, coordinates cellular defense against oxidative stress and inflammation. Ferritin measured clinically in plasma is usually apoferritin, a non–iron-containing molecule.

   
Normal range:

   Male: 23–336 ng/mL (in patients with normal iron stores, it should be >30 ng/mL)

   Females: 11–306 ng/mL

   Use

   Predict and monitor iron deficiency

   Determine response to iron therapy or compliance with treatment