Calcium Intolerance

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Calcium tolerance is often confused with lactose intolerance in health literature, but the two are not the same. Lactose intolerance occurs when a person has an inability to digest lactose, which is a sugar found in dairy products. According to P. T. Lascelles, M.D., author of "Diagnostic Function Tests in Chemical Pathology," calcium intolerance is a rare condition in which people have too much calcium in their systems as a result of overdose, or another condition.


Calcium intolerance is marked by the excretion of too much calcium into the urine, or hypercalciuria, or by too much calcium in the bloodstream, or hypercalcemia. This excretion of calcium occurs because the patient is intolerant to calcium and her system is getting rid of it instead of using it properly. Patients may have different symptoms depending on the type of calcium intolerance they have, but the typical symptoms include nausea, bloating, gas, vomiting, constipation or dry mouth.

Testing for Calcium Intolerance

Calcium intolerance can be identified by a calcium tolerance test in which the patient is given water to drink and a dose of calcium gluconate. Then the patient's blood serum levels of calcium, as well as levels of calcium in the urine, are measured over 24 hours after the test. A person with a normal response to calcium will only have a small rise in the calcium levels in his urine and/or blood, whereas someone with calcium intolerance will have a marked rise in either his levels of serum or urinary calcium.

Risk Factors

Calcium intolerance should be identified early to prevent kidney stones and osteporosis. This may be difficult to do because calcium intolerance may have no identifiable cause. However, it may have a genetic basis, according to Orson W. Moe and Olivier Bonny in the "Journal of the American Society of Nephrology." People with hyperparathyroidism are more at risk for hypercalciuria, writes Lascelles, and should be tested to ensure that they are getting adequate levels of calcium.


People with calcium intolerance must be carefully monitored because adding calcium supplements may cause toxic levels of calcium to form. The physician may supplement the patient by monitoring their diet or by giving them oral supplements of calcium to make up for the loss of calcium that can result from excreting all or most of their body's calcium. People with hypercalciuria may require diuretics to ensure that they are excreting the excess calcium, which may prevent kidney stones from forming.