Corrected Calcium Calculator
Purpose
The corrected calcium calculator helps adjust the calcium level (for further measurements) given the serum albumin and total calcium from the medical record of the patient.
There are two measurement units available for each of the variables used:
■ Serum albumin (g/dL or g/L);
■ Total calcium (mmol/L, mg/dL).
Formula
The formula used is the following:
■ Adjusted calcium = serum calcium [mg/dL] + 0.8 * (normal albumin - serum albumin [g/dL])
*where the normal albumin level is default at 4 g/dL therefore the formula becomes:
■ Corrected calcium = serum calcium + 0.8 * (4 - serum albumin)
Normal calcium levels are between 8.5 and 10.5 mg/dL or 2.1-2.6 mmol/L.
Calcium correction explained
The total calcium in the body is dependent on the level of serum albumin, which is the binding protein of calcium.
The adjusted or corrected calcium refers to the part of calcium which is ionized, the part that has a biological effect.
Usually, corrected calcium is calculated whenever albumin levels are not in the normal range, thus allowing an estimate as if albumin value were normal.
The two parameters used for the calculation are:
■ Serum albumin, measured in g/dL or g/L;
■ Total calcium, measured in either mg/dL or mmol/L.
The equation used is:
Adjusted calcium = serum calcium [mg/dL] + 0.8 * (normal albumin - serum albumin [g/dL])
*where the normal albumin level is default at 4 g/dL, thus the formula becomes:
Corrected calcium = serum calcium + 0.8 * (4 - serum albumin)
The value obtained can be used in determinations that follow up on suspicion of a calcium metabolism disorder.
Where hypoalbuminemia is present (low albumin levels), corrected calcium tends to be higher than total calcium.
The table below provides an indication of the recommended daily calcium intake:
| Infants | 260mg |
| Toddlers | 800mg |
| Children | 1200mg |
| Teenagers | 1300mg |
| Adults | 1000mg |
| Pregnant women | 1100mg |
| Adults over 50 | 1100mg |
| Adults over 70 | 1200mg |
Hypercalcaemia guidelines
When the right levels of calcium are not maintained, hypo or hyper-calcaemia occur. In the case of the latter, there are different stages, depending on the calcium levels:
| Hypercalcaemia | Total serum calcium levels in mg/dL |
| Mild | 10.5- 11.9 |
| Moderate | 12- 13.9 |
| Severe | 14- 16 |
Hypercalcaemia is caused by primary hyperparathyroidism (mostly in potmenopausal women) or by endocrine, electrolyte imbalances in malignancy.
Symptoms that affect the normal functioning of the central nervous system include confusion, fatigue, weakness or lethargy.
The cardiovascular and circulatory system may be affected by arrhythmias or syncope.
Renal symptoms consist of polyuria, dehydration or kidney stones and may lead to renal failure.
Nausea, abdominal pain, dyspepsia or gastric ulcer are hypercalcaemia effects on the digestive system.