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Thursday, May 23, 2013
Blood Calcium Questions
My son (17-yr.old) has had a CA-LC level of 10.0 or 10.1 mg/dL for the past 2 years, but his latest renal panel from last week came back with his CA-LC at 10.6 and flagged as "high." The nephrologist nevertheless listed the results as good w/no changes needed, so I guess she wasn`t concerned by it. My questions are these:
* How is CA-LC related to kidney function? *Should we be concerned about a rise of .5 mg/dL in CA-LC? * What might cause the CA-LC level to rise? * Is there anything dietary we should watch more closely?
I cannot actually answer your questions without knowing more about your son's medical history, particularly: why is he seeing a nephrologist at the age of 17? So you had best address your questions to her (the nephrologist); and in the meantime, here are some thoughts that occur to me about possible explanations for a high calcium level in a 17 year old who is being followed by a nephrologist:
1) In a person who is a little dehydrated (as someone might be just from not eating or drinking anything overnight and then having blood drawn in the morning; or from undergoing physical exercise and then not drinking anything afterwards), levels of several blood components, including calcium, can rise slightly because of the relative lack of water. This condition is rapidly corrected as soon as the person has something to drink.
2) In cases of chronic kidney disease, where kidney function is less than normal, people may develop a high blood calcium from "milk-alkali syndrome" if they consume a lot of calcium, as in a teenage boy who is drinking a lot of milk.
3) With advanced chronic kidney disease, if the disease has reached a stage where phosphate binders such as Phoslo or Tums are required, the intestines may absorb extra calcium contained in the medication, causing blood calcium to rise. This can be corrected by changing the phosphate binder to a non-calcium-containing one such as Renvela or Fosrenol.
4) Blood calcium can be elevated in a condition called "immobilization hypercalcemia" that can affect teenagers who have strong bones with a rapid rate of bone growth (such as teenage boys have) and who then have a sudden decrease in their amount of activity, as with a broken leg, or an illness that keeps them bedridden for a few days.
5) A benign hereditary condition called "familial hypocalciuric hypercalcemia" changes the way that the kidney handles calcium and may result in mildly elevated blood calcium levels. This condition is rare, but does not require any special treatment or worrying.
6) Overall, the commonest cause of a high calcium level in the general population is a benign tumor of the parathyroid glands (which are 4-6 pea-sized glands located in the neck). The calcium level may rise, and the diagnosis if made by checking blood parathyroid hormone (PTH) levels and doing scans of the neck to identify an enlarged, hyperactive gland. This condition can be stable for years and may or may not eventually require surgery.
I hope that this information helps, and please do not hesitate to ask your doctor for an explanation. Currently your son's calcium level is only mildly elevated, and should cause no harm; bad effects may be seen from much higher calcium levels, especially greater than 12.
Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University