Skip to content
Home » BLOG » What causes high calcium in the blood?

What causes high calcium in the blood?

The short answer:

A high calcium level in your blood (Hypercalcemia) is a serious health problem that may affect the normal functions of different body systems. The most common causes of high calcium in your blood are the increased secretion of parathyroid hormones, cancer, and chronic renal failure. Find more about the main causes and symptoms of high calcium in your blood in this article.

Key facts:

  • The high calcium blood level is known as hypercalcemia.
  • Hypercalcemia is defined as a serum calcium level higher than 10.5 mg/dL or 2.5 mmol/L.
  • A high calcium blood level is commonly caused by increased secretion of parathyroid hormones or caused by cancer.
  • Less common causes of increased calcium blood levels are thyroid intoxication, vitamin D, and certain drugs such as lithium, thiazide diuretics, vitamin A, and, calcium-containing antacid.
  • Symptoms of high calcium blood levels include constipation, nausea, vomiting, weakness, confusion, and heart problems in some cases.

What does high calcium blood level mean?

Causes of high calcium levels

Common causes of high calcium level

Less common causes of high calcium level

Symptoms of high calcium blood level.

How could a high calcium level affect your body?

FAQs

What does high calcium blood level mean?

The increase in your calcium blood level is known as hypercalcemia. It is a major clinical problem with serious complications. Hypercalcemia is suspected to occur in about 1 in 500 adults in the general adult population.

Hypercalcemia is defined as a serum calcium level higher than 10.5 mg/dL or 2.5 mmol/L. It may occur in up to 30% of patients with cancer with a bad prognosis (Ref).

The prevalence of hypercalcemia varies according to the population studied (Ref).

  • Persistent hypercalcemia has been reported to occur in up to 1% of individuals in the general population.
  • The prevalence of hypercalcemia in patients has been reported to be up to 3% in hospitalized patients.

What are the main causes of high calcium in the blood (hypercalcemia)?

Primary hyperparathyroidism and malignancy are the most common causes of hypercalcemia, It accounts for 80– 90% of cases of hypercalcemia.

Primary hyperparathyroidism is the major cause of hypercalcemia in the ambulatory population, comprising up to 60% of cases.

Hypercalcemia due to malignancy represents the leading cause in hospitalized patients (54–65%) (Ref).

The most common causes of hypercalcemia are the following:

  1. Primary hyperparathyroidism
  2. Hypercalcemia associated with malignancy
  3. Chronic renal failure

Less common causes of hypercalcemia include the following:

  1. Vitamin D-related hypercalcemia
  2. Endocrine problem (thyrotoxicosis)
  3. Drug-induced hypercalcemia

The most common causes of high calcium blood levels

Primary hyperparathyroidism

Parathyroid glands are small glands (the size of a grain of rice), located behind the thyroid gland at the bottom of your neck.

Hyperparathyroidism means increased secretions of parathyroid hormones. It is the most common cause of hypercalcemia among the ambulatory population. Hyperparathyroidism occurs mostly due to parathyroid adenoma (~85%), less frequently due to parathyroid hyperplasia (~15%), and rarely occurs as a result of parathyroid carcinoma.

Primary hyperparathyroidism is more common in women than men (2.5:1), especially in older women (Ref).

Hypercalcemia associated with malignancy

It is the most common cause of hypercalcemia among hospitalized patients (Ref). Up to 30% of individuals with cancer have hypercalcemia.

Patients with hypercalcemia due to malignancy commonly have more elevated levels of calcium than those seen in hypercalcemic patients due to primary hyperparathyroidism.

The calcium levels in case of hypercalcemia due to malignancy may be greater than 3.25 mmol/L (13.0 mg/dL).

This type of hypercalcemia may result from the extra conversion of 25(OH) vitamin D to 1,25-dihydroxy vitamin D (the active form of vitamin D) in the kidney.

Chronic renal failure

Chronic renal failure is a relatively common cause of hypercalcemia. Patients with chronic renal failure usually have secondary hyperparathyroidism with low or normal calcium levels.

However, in this case, hypercalcemia may result from the treatment with calcium, phosphate binders, and vitamin D supplements.

Patients treated with calcium salts and vitamin D to control calcium, and phosphate blood levels, and parathyroid homeostasis can lead to dynamic bone disease and consequently, reduce the uptake of calcium by bone, and as a result, hypercalcemia develops.

Less common causes of hypercalcemia

Hypercalcemia due to vitamin D intoxication

Vitamin D intoxication is a less common cause that may lead to hypercalcemia.

Vitamin D intoxication could result from:

  • Excessive intake of exogenous vitamin D and its analogs.
  • Overproduction of vitamin D by excessive conversion of 25 OH vitamin D to the active form 1, 25 OH vitamin D.

Endocrine-induced hypercalcemia

Thyroid gland problems (Thyrotoxicosis) frequently lead to mild hypercalcemia.

Thyrotoxicosis means you have too much thyroid hormone in your blood. Thyrotoxicosis increases your calcium blood level due to thyroid hormones mediated boon resorption.

Bone resorption is a process by which osteoclast cells break down your bones and release their mineral content.

In the case of hypercalcemia caused by thyroid intoxication, the hypercalcemia should be treated after adjusting thyroid hormones first.

Thyrotoxicosis could result from the following:

  • Primary hyperthyroidism.
  • Patients with hypothyroidism are treated with thyroid hormones as replacement therapy.
  • Patients with thyroid cancer who are treated with thyroid hormones as a suppressive therapy.

Drug-induced hypercalcemia

Certain drugs can increase your calcium blood levels.

It is not a common cause of hypercalcemia.

What are the most common drugs that cause hypercalcemia?

  • Milk-alkali syndrome
  • Calcium-containing antacids: Ingestion of antacid-containing calcium might increase your calcium blood levels.
  • Thiazide diuretics: Thiazide diuretics decrease calcium loss in urine and hence, increase your calcium blood level.
  • Lithium: it is reported to increase parathyroid hormone secretion leading to hypercalcemia.
  • Vitamin A: vitamin A intoxication increases your bone resorption and consequently, blood calcium level is increased.

What are the symptoms of high calcium in your blood?

Symptoms are hypercalcemia are nonspecific and include the following

  • Fatigue and weakness
  • Nausea
  • Vomiting
  • Constipation
  • Abdominal pain
  • Bone pain
  • Polyuria
  • Confusion
  • Coma in severe cases.
  • Hypercalcemia may cause cardiac arrhythmias, renal vasoconstriction, decreased urine volume with acute kidney injury, and nephrogenic diabetes insipidus.

How could a high calcium level affect your body?

The symptoms of elevated calcium blood levels could harmfully affect the function of different body organs and systems as follow:

Effect on your stomach:

Hypercalcemia leads to the following:

  • Stomach upset.
  • Nausea
  • Vomiting.

Gastrointestinal tract:

Constipation is the most common symptom of hypercalcemia.

Renal system

High calcium blood levels could affect kidney functions leading to frequent urination and you become a thirst.

Also, higher calcium level increase your risk to develop kidney stones.

Effect on muscles and bones

Increased blood calcium levels commonly result from bone resorption (bone breakdown). Therefore, high calcium blood levels mean you have weak bones leading to muscle and bone pain.

Cardiovascular system:

Severe but rare symptoms of elevated calcium blood levels related to your heart. This includes increased heart rate, fainting, and cardiac arrhythmias.

Effects on your brain:

High calcium blood levels could lead to confusion, lethargy, and coma in severe cases.

In mild cases, patients may suffer from anxiety, depression, and cognitive changes.

in case of severe hypercalcemia, altered mental status, psychosis, confusion, lethargy, and coma hallmark severe hypercalcemia (Ref).

FAQs

1. Can high calcium affect your memory?

Yes, a high calcium blood level could affect your brain function and hence, your memory might be negatively affected.

A higher calcium level in your neurons could increase the risk of memory loss for those afflicted with Alzheimer’s disease.

Moreover, a study showed that calcium supplementation may increase the risk of developing dementia in elderly Sweden women with after 5 years of follow-up.

2. Can high calcium affect your eyes?

Yes, a high calcium blood level could affect your eyes.

Band keratopathy may result in patients with a high calcium level.

Band keratopathy (calcified band keratopathy) involves calcium deposition in the corneal layers due to elevated calcium blood level.

3. Can high calcium level affect your teeth?

Yes, a high calcium level could affect your teeth.

Calcium is an essential element for healthy and strong bones and teeth. However, high calcium blood level could negatively affect your teeth leading to the following:

  • Teeth sensitivity.
  • Teeth will not be aligned properly (Malocclusion).
  • Weakness of your jaw bones