For bodies to work efficiently, they need to be supplied with the right balance of vitamins and minerals. Discover what happens when we get too much of just one essential mineral - calcium.
Dr Trisha Macnair last medically reviewed this article in March 2009.
Calcium is a mineral that's vital for the development of healthy bones and teeth - 99 per cent of the calcium in our bodies is found here. It's also needed for muscle contraction, regulation of the heartbeat and formation of blood clots. A long-term shortage of calcium can lead to osteoporosis (brittle-bone disease).
The four pea-sized parathyroid glands (found at the front of the neck) are responsible for regulating the body's calcium levels. These small glands, which are embedded in the tissue of the thyroid gland in the neck, detect fluctuations in the level of calcium in the blood.
There are times when this delicate balance is upset and too much calcium enters the blood. If levels rise too much, the glands decrease the secretion of the parathyroid hormone (PTH) and calcium levels return to normal again.
Too much calcium in the blood may cause:
Hypercalcaemia can also cause more serious problems such as depression, dehydration, bone fractures, kidney stones and sudden heart attacks.
One of the commonest causes of hypercalcaemia is cancer. Up to 20% of people with cancer have high calcium levels, especially with cancers of the breast, lung, head and neck, and certain blood cancers.
Hypercalcaemia occurs in cancer for two main reasons – either the cancer has spread to the bones and is breaking down bone tissue, or the cancer cells are secreting hormones which can increase calcium levels.
An overproduction of PTH may also responsible for hypercalcaemia; this is often caused by a tumour in one or more of the parathyroid glands. Excess production of PTH may occur to compensate for a malfunction in one of the body's other calcium-balancing mechanisms; for example, when the kidneys aren't working properly or when there's a deficiency of vitamin D.
Treatment depends on how high the levels of calcium are, symptoms and suspected underlying cause. Sometimes, no treatment is necessary; at other times, intravenous drugs will be given to lower the calcium levels. Removal of a primary cause, such as a hormone secreting cancer, may also be important.
Surgery may also be needed to remove the parathyroid glands if they're the source of the problem.
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