Blood test

High calcium level in the blood

Blood test
High calcium level in the blood
Last update: 05/03/2020

What is high calcium level in blood called?

  • Hypercalcaemia
  • Hypercalcemia

What is the normal level of calcium in the blood?

If you need to know which are the calcium reference ranges or you require more information about the role of calcium in the blood, you can visit normal calcium level in the blood

What does a high blood calcium level mean?

Calcium in the blood can be free or bound to proteins or other substances. Free calcium is also called ionized calcium. 40% of calcium in the blood is free (ionized), 50% is bound to proteins (albumin mainly) and only 10% is bound to other elements (phosphorus, etc.)

In this document, we speak about total blood calcium. Sometimes, a blood test only measures free or ionized calcium, so the results are more or less 40% of the ranges showed above.

Blood albumin levels bound to calcium can alter the total blood calcium level. However, albumin level does not alter ionized calcium. Calcium biological functions depend mainly on ionized calcium rather than on total calcium.

Hypercalcemia or high blood calcium levels are typical of multiple medical condition, including hyperparathyroidism, Addison's disease, hyperthyroidism, etc. It can been seen also in case of bone cancer, if vitamin D intake is excessive or if you are taking thiazide diuretics.

Calcium blood values are usually given in mg/dl but sometimes you can see those values in mmol/l following the International System of Units (SI). In case your values are in mmol/l you can convert them using this tool:

  • Mild hypercalcemia (10.9 - 11.5 mg/dL in adults):

    Calcium blood levels are higher than normal but if you do not have any other symptom it is usually not a concern. Maybe you take too much calcium or vitamin D in your diet. It is advisable to limit your dairy and milk intake and to drink more water every day.

  • Moderate hypercalcemia (11.5 - 12.5 mg/dL in adults):

    Calcium blood levels are moderately high and you may require medication to lower this level if your doctor considers it appropriate.

  • Marked hypercalcemia (12.5 - 14 mg/dL in adults):

    Your calcium blood level is so high that you are probably suffering from bone pain, muscle weakness, confusion or fatigue.

    You may require hospitalization because it is very important to avoid any possible damage to your kidneys and bones.

  • Severe hypercalcemia (> 14 mg/dL in adults):

    At these high levels of calcium in blood, coma and cardiac arrest are a possibility. You must find urgent medical attention.

Which factors can raise calcium blood levels?

  • Long-term immobilization
  • Drugs
    • Antacids
    • Antiestrogens
      • Tamoxifen
    • Antihypertensives
      • Hydralazine
    • Diuretics
      • Thiazides
    • Psychotropic drugs
      • Lithium
    • Thyroxine

Which diseases can raise your calcium blood levels?

There are many medical conditions why the calcium blood levels can be higher than normal:

What can I do to lower calcium blood levels?

If your calcium blood level is slightly high, you can consider the following tips:

  • Drink plenty of fluids (water, juice, etc.). It can help renal calcium excretion.
  • Decrease calcium intake. Dairy products contain a lot of calcium.
  • Decrease vitamin D intake. Oily fish (sardines, herrings, anchovies, tuna, etc. ), eggs and dairy products have some of the highest quantities of vitamin D

Where can I find more information about calcium in the blood?

You can visit our pages about:

Which values are considered a high calcium level in the blood?

The following values are considered to be above the normal range:

IMPORTANT: These levels are expressed in mg/dl. They are an example of a healthy man of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

Mild hypercalcemia
11 mg/dL11.1 mg/dL11.2 mg/dL11.3 mg/dL11.4 mg/dL11.5 mg/dL  
Moderate hypercalcemia
11.6 mg/dL11.7 mg/dL11.8 mg/dL11.9 mg/dL12 mg/dL12.1 mg/dL12.2 mg/dL12.3 mg/dL
12.4 mg/dL12.5 mg/dL      
Marked hypercalcemia
12.6 mg/dL12.7 mg/dL12.8 mg/dL12.9 mg/dL13 mg/dL13.1 mg/dL13.2 mg/dL13.3 mg/dL
13.4 mg/dL13.5 mg/dL13.6 mg/dL13.7 mg/dL13.8 mg/dL13.9 mg/dL14 mg/dL 
Severe hypercalcemia
14.1 mg/dL14.2 mg/dL14.3 mg/dL14.4 mg/dL14.5 mg/dL14.6 mg/dL14.7 mg/dL14.8 mg/dL
14.9 mg/dL15 mg/dL15.1 mg/dL15.2 mg/dL15.3 mg/dL15.4 mg/dL15.5 mg/dL15.6 mg/dL
15.7 mg/dL15.8 mg/dL15.9 mg/dL16 mg/dL    
Medically reviewed by Javier Muga Bustamante Ph.D. on 05/03/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 493.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David E. Bruns, Barbara G. Sawyer. WB Saunders Company, 2008. Pag 712. ISBN: 978-0-7216-3865-2.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Available on:
  • Thomas L, ed. Clinical Laboratory Diagnostics Use and Assessment of Clinical Laboratory Results, 1st ed. Frankfurt/Main: TH-Books Verlagsgesellschaft, 1998:231-241.

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