Identification of abnormal physiologic states causing excess or suppressed absorption or excretion of calcium
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Calcium is the fifth most common element in the body. It is a fundamental element necessary to form electrical gradients across membranes, it is an essential cofactor for many enzymes, and it is the main constituent in bone. Under normal physiologic conditions, the concentration of calcium in serum and in cells is tightly controlled.
Calcium is excreted in both the urine and the feces.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Reference values apply to all ages.
Increased fecal excretion of calcium is observed in diseases involving high calcium turnover such as hyperparathyroidism, vitamin D intoxication, diseases that destroy bone (such as multiple myeloma), metastasis from prostatic cancer, and following calcium supplementation.
Patients with absorptive hypercalciuria (increased gut absorption) will have low fecal calcium with dietary restriction, facilitating differentiation from patients with hypercalcuria caused by hyperparathyroidism, hyperthyroidism, Paget's disease, or "renal leak" type of calciuria as seen in renal tubular acidosis.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Gadolinium is known to interfere with most metals tests. If gadolinium-containing contrast media has been administered a specimen can not be collected for 48 hours.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Abrams SA, Schanler RJ, Yergey AL, et al: Compartmental analysis of calcium metabolism in very-low-birth-weight infants. Pediatr Res 1994 October;36(4):424-428
2. Ditscheid B, Keller S, Jahreis G: Cholesterol metabolism is affected by calcium phosphate supplementation in humans. J Nutr 2005;135(7):1678-1682
3. Nishimuta M, Inoue N, Kodama N, et al: Moisture and mineral content of human feces - high fecal moisture is associated with increased sodium and decreased potassium content. J. Nutr Sci Vitaminol 2006 April;56:121-126