The measurement of calcemia, that is to say the level of calcium in the blood, is indicated as part of a complete assessment or for very specific indications. What do values that are too high or too low mean?
“Calcium is mainly found (99%) in the bone mineral (bones, teeth) in the form of hydroxyapatite crystals. A tiny fraction is contained in the extracellular fluid” explains Dr. Lucie Lemeunie rheumatologist at Saint-Antoine Hospital in Paris. The remaining 1% has a role of cofactor as activator of blood coagulation, neuromuscular excitability and gastric acid secretion phenomena. Calcium enters the body in the intestine and goes to the organs that need it through the blood. Serum calcium refers to the level of calcium in the blood. How to calculate serum calcium corrected? When to measure serum calcium? What do rates too low or too high?
Definition: what is calcemia?
Serum calcium means the level of calcium in the blood. It is essential to the body and is involved in particular in the bone mineralization, the phenomena of blood coagulation, and muscle physiology. “Calcium abnormalities should always be interpreted taking into account the concomitant parathyroid hormone value (we speak of a “calcium-PTH” pair)”, details Dr. Lucie Lemeunier.
Circulating inside the blood plasma, calcium is present in two distinct forms. The first is ionized calcium which has an electrical charge. The second, non-ionized calcium, binds to plasma albumin. By binding to this protein, the calcium does not dissolve outside the plasma. In the event of a drop in albuminemia, it is possible to observe a false hypocalcemia while the physiological rate of ionized calcium is correct. Thus is it necessary toapply the corrected calcium formula : Ca measured in mmol/L + 0.025 x (40 – serum albumin in g/l). It will be low if it is below 2.20 mmol/l.
Why monitor serum calcium?
The determination of calcium in the blood, calcemia can be carried out in different specific situations: renal failure, cancer (suspicion, follow-up), suspicion of digestive malabsorption, osteoporosis assessment.
What is the normal serum calcium level?
“In adulthood, the normal values of total serum calcium are between 2.20 mmol/L and 2.60 mmol/L. It’s necessary jointly measure the albumin level (corrected calcium) and the PTH ; in certain cases, a particular determination of the calcemia called ‘ionized calcemia’ can be requested and the usual normal values are between 1.15 and 1.30 mmol/L”, details the specialist.
What is a low calcium level?
When the calcium level is less than 2.20 mmol/l, we are talking hypocalcemia. Hypocalcaemia, low blood calcium concentration, possibly related to a vitamin D deficiency. “It can translate into cramps, tetany crisis most often in acute and severe forms”, says Dr. Lemeunier. Low blood calcium levels can also be caused by: Absorptive defect from the intestine, rickets or hypoparathyroidism.
What is a high calcium level?
“When the calcium level is greater than 2.60 mmol/l, it is called hypercalcemia. A distinction is made between parathyroid and non-parathyroid origins. (example: blood disease, bone metastasis). Primary hyperparathyroidism may result in bone manifestations (osteoporosis), renal (lithiasis or urinary stones)“describes Dr. Lemeunier. Hypercalcemia can manifest as a fatigue, loss of appetite, vomiting, thirst and more frequent urination.
► Be aware that the The results of a biological analysis alone do not constitute a diagnosis. It is therefore important to consult a doctor in order to plan with him additional examinations or possible treatment. A good result is, for your doctor, an important indication of your state of health, just as much as a bad one. Results may also vary depending on the technique used by the laboratory.
Thanks to Dr. Lucie Lemeunier, rheumatologist at Saint-Antoine Hospital in Paris.