A calcium level of 6.6
| Where it fallscommonly reported adult reference ranges | Markedly low |
|---|---|
| Calcium | 6.6mg/dL |
| Usual reference range | 8.6 – 10.2mg/dL |
| Same result in mmol/L | 1.65mmol/L |
| Markedly lowthis reading | under 7mg/dL |
| Below the reference range | 7 – 8.5mg/dL |
| Normal | 8.6 – 10.2mg/dL |
| Above the reference range | 10.3 – 11.9mg/dL |
| Markedly raised | 12 and abovemg/dL |
Notes
- A calcium of 6.6 mg/dL is outside the range a web page should be the end of. Repeat the measurement, and contact a doctor rather than reading further. If it comes with chest pain, breathlessness, confusion, weakness or a change in vision, treat it as an emergency.
- Reference ranges differ between laboratories. The bands above follow commonly reported adult reference ranges. Your own report prints the range its analyser was calibrated against, and that printed range is the one to compare against — a difference of a few units between labs is normal and does not mean either is wrong.
- Total calcium has to be read against albumin. Roughly half the calcium in blood is bound to albumin and is not biologically active, so a low albumin drags the total down without the active fraction changing. The usual correction adds 0.8 mg/dL for every 1 g/dL the albumin sits below 4.0. A total of 6.6 mg/dL in someone with an albumin of 3.0 is really behaving like 7.4.
- A persistently raised calcium has a short list of causes. Primary hyperparathyroidism and malignancy account for the large majority in adults, and separating them is what the parathyroid hormone level on the follow-up sample is for: high or inappropriately normal PTH points to the parathyroids, suppressed PTH points elsewhere.
What calcium of 6.6 mg/dL means
A reading of 6.6 mg/dL falls in Markedly low by commonly reported adult reference ranges.
The usual reference range is 8.6 – 10.2 mg/dL.
Reading it next to the rest of the picture
A single figure is a snapshot. What somebody experienced does with it is set by what sits around it — the other figures on the same report, the history behind them, and what the previous result was. Two people can hand over the same number and leave with different advice, and neither has been given the wrong answer.
That is also why the bands on this page are drawn from a named source rather than a rounded rule of thumb. A threshold is a decision point somebody argued for in print, not a law of nature, and knowing which document a line comes from is what lets you tell a meaningful result from a borderline one.
Nearby sizes
Read more
- CBC Normal Ranges — What Each Line on the Result MeansA value marked high or low on a CBC is common and is often not significant on its own. The pattern across lines is what a clinician reads.
- eGFR Normal Range: Above 90, and the Stages Below IteGFR is an estimate built from creatinine, age and sex — and the estimate is better than the raw creatinine it comes from, for a reason worth understanding.
- TSH Normal Range: 0.4–4.0 mIU/L, and the Number Moves BackwardsTSH runs opposite to the gland it measures. High TSH means the thyroid is underactive, and that inversion catches almost everyone reading their own result.
- Cholesterol Numbers: What Total, LDL, HDL and Triglycerides MeanA lipid panel reports four numbers and the one printed largest — total cholesterol — is the least useful of them.