RENAL-CALCIUM BALANCE

SUMMARY

1. Calcium is absorbed from the duodenum, stored in the bone, and excreted by the kidneys.

2. Regulated by PTH and vitamin D metabolites, both affect rates of absorption in the kidneys and gut and rates of resorption of bone.

3. The measured plasma calcium concentration is a total of free/ionized calcium (45%), calcium bound to albu­min (40%), and calcium bound to other substances (15%).

4. Ionized calcium is the state available for imme­diate use by the body and correlates with consequences of hyper- or hypocalcemia.

5. If albumin decreases, the measured plasma calcium decreases.



Image: Dr. Appukutty Manickam.

Reference(s)

Barrett, K.E., Barman, S.M., Brooks, H.L., X, J. and Ganong, W.F. (2019). Ganong’s review of medical physiology. 26th ed. New York: Mcgraw-Hill Education