Hypercalcaemia

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.

Features and Causes of Hypercalcaemia

Those with a raised blood calcium level, hypercalcaemia, will typically suffer from:

• Fatigue
• Depression
• Excessive thirst and increased urination
• Kidney stones
• Bone pains and abdominal pains. 

Causes include:

• Cancer especially if there is spread to the bones
• Drugs – thiazide diuretics, lithium and ,
• Increased sensitivity to vitamin D as can occur with sarcoidosis, TB and lymphoma
• Excessive intake of vitamin D or calcium. 
• Overproduction of calcium controlling hormone, parathormone

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,

Advice for Those with Hypercalcaemia

• Do not take calcium or vitamin D supplements without medical advice
• Doses of vitamin D up to the Guidance Level of 25 ug per day may be safe in those who do not have vitamin D sensitivity but medical advice should be sought
• Supplements of vitamin A – retinol and high dose beta-carotene should not be taken without assessment of serum retinol and medical advice
• Liver and liver products, which are a rich dietary source of retinol, should not be consumed without assessment of serum retinol and medical advice
• Most multivitamins and cod liver oil preparations contain enough vitamin D and retinol to be potentially of mild harm to some of those with hypercalcaemia

Additional Advice for Those Taking Long-Term Calcium and Vitamin D Supplements

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;

• Those who are over 65 years of age may need to have their serum calcium and renal function checked every two to three years as changes in these measures would alter the advisability of taking these supplements.  This interval is likely to be similar to that at which measures of bone mineral density are undertaken and the risk of renal or calcium abnormalities developing rise significantly with increasing age
• The need for supplemental vitamin D may rise with increasing age, reducing sun exposure, dietary change and deteriorating renal function
• The safety of supplemental calcium is a little uncertain as in elderly women high doses have been associated with an increased risk of vascular events.  Thus benefit must always be balanced by risk.
• The development of hypercalcaemia, renal disease, kidney stones or vascular disease should result in a reappraisal of the risks and benefits of long-term calcium and vitamin D supplementation.