How hypercalcaemia can lead to constipation

Hypercalcemia (Hypercalcemia, high level of calcium in the blood)

Hypercalcemia is when the calcium level in the blood is too high. While a slightly increased value causes no or only slight discomfort, a very high calcium value can be life-threatening.

Short version:

  • Calcium is a mineral that is 98% bound in the bone substance.
  • If the calcium level in the blood is increased, it is called hypercalcemia.
  • Hypercalcemia usually occurs as a result of increased bone loss.
  • The reasons for this can be very different.
  • The diagnosis of hypercalcaemia is usually made through a blood test.


Calcium is the most important mineral in the human body in terms of quantity. About 98% of the total calcium (around 1,000 g) is bound in the bone tissue and tooth enamel and ensures the strength and stability of these tissues. The remaining 2% circulate in the body. Half of the circulating part is free (ionized) calcium, the other half is bound to proteins (albumin and globulin) or inorganic molecules (bicarbonate or phosphate).

Together with potassium, magnesium, sodium, phosphorus or chloride, calcium is one of the electrolytes, which in turn are involved in vital metabolic functions in the body. However, they are all not produced by the body itself, but must be supplied with food and drink.

What does the body need calcium for?

  • Bone Mineralization: Calcium is an important component of teeth and bones.
  • Nerve and muscle excitability: nerve impulses are converted into muscle activity.
  • Blood clotting
  • Release of hormones
  • Regulation of enzyme activity

However, these functions can only work correctly if the concentration in the blood is strictly adhered to. The regulation of this concentration is controlled by various hormones:

Parathyroid hormone- the most important regulator: It is formed in the parathyroid gland and, among other things, increases the calcium level by mobilizing calcium from the bones. At the same time, calcium is "retained" when the urine is concentrated in the kidneys, i.e. less is excreted.

Calcitonin: It is made in the thyroid gland and lowers calcium levels by promoting the incorporation of calcium into the bones. In contrast to fish, this hormone is of very little importance in humans.

Vitamin D: The precursor of this hormone is either absorbed from food through the intestines or formed in the skin under the action of UV and converted into an active form via various intermediate stages in the liver and kidneys, but also in many other cell systems. It increases calcium levels by primarily promoting the absorption of calcium from the intestines.

What is hypercalcemia?

Hypercalcemia is a high level of calcium in the blood. The normal value for total calcium in the blood is 2.2–2.6 mmol / l. If a total calcium of> 2.6 mmol / l or ionized calcium> 1.3 mmol / l is found in the laboratory, hypercalcaemia is present. A total calcium value of> 3.5 mmol / l is acutely life-threatening.

What are the causes of hypercalcemia?

An excessively high level of calcium in the blood can have various causes, which must be clarified by a doctor in each case. However, it usually arises as a result of increased bone loss.

Causes for this can be:

  • Parathyroid disorder: primary hyperparathyroidism
  • Malignant tumors: lung or breast cancer, prostate cancer, multiple myeloma
  • Hyperthyroidism: overactive thyroid gland
  • Lymphoma
  • Bone loss due to lack of movement (immobilization)
  • Sarcoid
  • Calcium supplements (e.g. calcium carbonate as a phosphate binder in renal insufficiency)
  • Medication: thiazide diuretics, tamoxifen medication, excessive vitamin D intake
  • nutrition
  • Diseases with bone involvement

What are the symptoms?

Symptoms usually only appear at values> 2.8–2.9 mmol / l. However, these are very unspecific - especially if they are only slightly increased:

  • increased need to urinate
  • increased thirst
  • difficult bowel movements, constipation
  • Nausea, vomiting

The more calcium circulates in the blood, the more severe the symptoms become. If the values ​​are high, then:

  • Polyuria, dehydration, kidney stones
  • Fatigue, muscle weakness, symptoms of paralysis
  • Arrhythmias (irregular heartbeat), hypertension (high blood pressure)
  • Weight loss, nausea, vomiting, constipation, stomach or duodenal ulcer, pancreatitis
  • Loss of drive, impaired consciousness up to a coma
  • Incorporation of calcium (calcification) in the kidneys, stomach and lungs

Calcium poisoning (intoxication) can be acutely life-threatening. Typical symptoms are:

  • Apathy, impaired consciousness and even coma
  • Dehydration
  • Renal failure
  • Tachycardia ("racing heart")
  • Cardiac arrest

How is the diagnosis made?

(Mild) hypercalcaemia is often only discovered during routine blood tests.

Due to the binding of calcium to proteins (especially albumin), the measured value of the total calcium concentration in the blood can be too high or too low without actually increasing or decreasing the biologically effective ionized calcium. If the albumin or total protein concentration is not within the normal values, the total calcium value must be corrected mathematically in the laboratory.

The determination of parathyroid hormone, vitamin D and the calcium concentration in the urine allow essential conclusions to be drawn about the cause of the increase in calcium.

  • Clinical examination
  • Neurological examination
  • ECG: QT time shortening, AV block, arrhythmias
  • Urinary excretion: polyuria
  • X-ray: calcification, bone resorption, tumors, sarcoid

How is the therapy carried out?

The treatment needed depends on the extent and cause of the hypercalcemia. If a causal underlying disease such as a tumor is found, it must be treated. Symptomatic therapy is designed to promote calcium excretion and reduce the breakdown of calcium from the bones.

  • Mild hypercalcemia (total calcium ≤ 3.0 mmol / L):

Drink plenty of fluids (no mineral water containing calcium), infusions with isotonic saline solution as a fluid substitute; oral phosphate reduces the absorption of calcium; Loop diuretics (increasing urine flow)

  • Moderately severe hypercalcemia (total calcium 3.0 - ≤ 3.5 mmol / L):

Bisphosphonate, corticosteroids, possibly calcitonin (slows the release of calcium from the bones)

  • Severe hypercalcemia (> 3.5 mmol / L):

Blood washing (dialysis)

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Astrid Leitner
Medical review:
Univ.Prof. Dr. Harald Dobnig
Editorial editing:
Mag. Julia Wild

Status of medical information:

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