Testing Calcium in Blood and Understanding Its Results

Calcium is an important mineral required for many important functions of the body, including muscle contraction, impulse transmission in the nerves, heart muscle functioning etc.

Distribution of Calcium in the Body

98% of body’s calcium is present in the bones and teeth. It’s only the remaining 2% that is present in the blood.

Serum calcium may be present in free form, bounded to protein molecule, ionized form etc.

Doctors measure only the serum calcium to help diagnose the disease states.

Reference Range for Calcium Values

Serum calcium is maintained within a narrow range in our body. The values are between 8.5 to 10.2 mg/dl

Hypocalcemia (Low serum calcium)- Any value below 8.0 mg/dl

Mild: 10.5 to 12 mg/dl
Moderate: 12 to 14  mg/dl
Critical: 14 mg/dl or higher

Low Serum Calcium

A low Ca level may give symptoms like fatigue, indigestion, muscle cramps, osteoporosis and dizziness or other nervous system symptoms.

Common Causes of Hypocalcemia

  • Hypoparathyroidism- It is one of the commonest cause of having a low calcium in the body. This hormone, PTH, is responsible for maintaining the calcium balance in the body.
  • Inadequate intake of calcium in the diet.
  • Improper absorption due to any gut problem
  • Vitamin D deficiency
  • Magnesium deficiency
  • Pancreatitis
  • Kidney or liver diseases

Mainly, the intestine, bones and kidney decide the movement of calcium in or out of the ECF.

In general, when blood is not getting enough calcium via diet, it starts taking it from the bones, rendering them weaker in a long run.

High Calcium in the Blood

A patient with higher Ca levels of calcium can exhibit hypertension or high blood pressure. He may have muscle twitching and other symptoms.

Common Causes of Hypercalcemia

  • Too much intake of calcium or vitamin D. This exclude the amount being taken in the form of diet, like dairy products or vegetables.
  • Hyperparathyroidism- One of the commonest cause of having high blood calcium levels.
  • Some infective conditions that cause granulomas, such as, tuberculosis, fungal infections and other mycobacterial infections.
  • Cancers which metastasize to the bones
  • Bone cancers like multiple myeloma
  • Hyperthyroidism
  • Medications like, lithium, tamoxifen, thiazides etc.
  • Long term bed rest

Calcium correction is very important. Its levels need to be maintained within a narrow range for a proper functioning of our nerves and all muscles, including those of heart, intestine and limbs.

Medical Advice (Q&As) on “Serum Calcium Lab Test – If Ca Blood Levels Normal Low or High

    1. Buddy M.D. Post author

      You may feel some tingling or numbness in your feet / palms.

      Low calcium affects the nerves and muscles of the body. You may have pain in certain group of muscles, like those of the calf or thigh.


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