Hypercalcaemia is the medical term for a raised level of calcium in the blood, which is a not uncommon finding in older people. Its presence has important implications for those who are taking or want to take supplements.
Calcium is a bulk mineral which the body needs for both structural purposes – the formation of bones and teeth, as well as functional purposes – interactions with many enzymes and controlling nerve and muscle impulses. There are several hormones that keep the level of calcium in the blood at a steady level. A low blood calcium level is a rare event but a raised blood calcium is a not uncommon finding and is often found fortuitously in older people.
Those with a raised blood calcium level, hypercalcaemia, will typically suffer from:
Parathyroid hormone comes from the four minute parathyroid glands, which are in the neck just behind the thyroid gland. It acts to raise blood calcium by increasing its mobilisation from bone. Hyperparathyroidism is the commonest cause of an elevated blood calcium level in older people especially those who are not seriously ill and may be present in between 0.1% and 1.0% of the older population.
Hyperparathyroidism results in an elevation in blood calcium levels, often with a reduced level of phosphate and a raised level of parathyroid hormone. Many patients have only mild symptoms of fatigue. The production of parathyroid hormone can also be increased by an excess of vitamin A derived from either dietary sources (liver) or from supplements or secondary to renal failure, which reduces the excretion of vitamin A.
According to the National Diet and Nutrition Surveys of the British population, 13% of adults and the 25% of the free-living elderly have relatively high blood levels of retinol (plasma level >2.5 umol/l) [NDNS]. Elevated blood levels have been associated with an increased risk of osteoporosis,
Many people take calcium and vitamin D for the treatment or prevention of osteoporosis. These supplements are usually very safe and the doses used typically fall within current UK Safe Upper Levels or Guidance Levels. However because the evidence that determines the balance between benefit and risk may change and in particular because an individual’s health risks may also change it may be prudent to be aware of the following;