Calcium levels in the blood are controlled in a very tight range - in the UK levels are given on blood tests such that the normal range is between 2.2 and 2.55 mmol/l. This varies between laboratories and hospitals but not by much.
Key Point 1 - A high calcium is never normal
Calcium levels are controlled by the parathyroid glands which make parathyroid hormone (PTH). The 4 parathyroid glands have a really big blood supply and can monitor calcium levels really effectively. Contol of calicum is in a very narrow range.
Key Point 2 - Calcium levels will fluctuate on a day to day basis
So calcium levels if checked and are just outside normal can be rechecked and may a few days later be in the normal range. Some patients with parathyroid disease who have calcium levels that are marginally elevated will therefore dip into normal from time to time - this can make the diagnosis difficult.
Key Point 3 - What to do if calcium is high
Calcium levels should be rechecked along with a PTH level. If the calcium is high PTH levels should be almost zero because like your boiler their internal thermostat (measuring calcium not temperature) should have switched them off.
If PTH levels are in the 'normal' range and calcium is high you almost certainly have parathyroid disease as the calcium levels are inappropriately elevated as they should be near zero.
Key Point 4 - Symptoms are not linked to calcium level
Many patients will have marginally elevated calcium levels and yet have terrible symptoms. Some will have very high calcium and no symptoms. The absolute numbers are of no great relevance. All patients with parathyroid disease should have a discussion about treatment with someone who understands the disease.
More information on:
Parathyroid Surgery
Parathyroid and Minimal Access Thyroid Surgery
