Hypercalcaemia (British English) or hypercalcemia (American English) is an elevated calcium (Ca2+) level in the blood. (Normal range: 9–10.5 mg/dL or 2.2–2.6 mmol/L). It can be an asymptomatic laboratory finding, but because an elevated calcium level is often indicative of other diseases, a workup should be undertaken if it persists. It can be due to excessive skeletal calcium release, increased intestinal calcium absorption, or decreased renal calcium excretion.
The neuromuscular symptoms of hypercalcemia are caused by a negative bathmotropic effect due to the increased interaction of calcium with sodium channels. Since calcium blocks sodium channels and inhibits depolarization of nerve and muscle fibers, increased calcium raises the threshold for depolarization. There is a general mnemonic for remembering the effects of hypercalcaemia: "Stones, Bones, Groans, Thrones and Psychiatric Overtones"
Hypercalcaemia can increase gastrin production, leading to increased acidity so peptic ulcers may also occur.
Symptoms are more common at high calcium blood values (12.0 mg/dL or 3 mmol/l). Severe hypercalcaemia (above 15–16 mg/dL or 3.75–4 mmol/l) is considered a medical emergency: at these levels, coma and cardiac arrest can result. The high levels of calcium ions decrease the neuron membrane permeability to sodium ions, thus decreasing the excitability, which leads to hypotonicity of smooth and striated muscle. This explains the fatigue, muscle weakness, low tone and sluggish reflexes in muscle groups. The sluggish nerves also explain drowsiness, confusion, hallucinations, stupor and / or coma. In the gut this causes constipation. Hypocalcaemia causes the opposite by the same mechanism.
hydration is needed because many patients are dehydrated due to vomiting or renal defects in concentrating urine.
increased salt intake also can increase body fluid volume as well as increasing urine sodium excretion, which further increases urinary potassium excretion.
after rehydration, a loop diuretic such as furosemide can be given to permit continued large volume intravenous salt and water replacement while minimizing the risk of blood volume overload and pulmonary oedema. In addition, loop diuretics tend to depress renal calcium reabsorption thereby helping to lower blood calcium levels
can usually decrease serum calcium by 1–3 mg/dL within 24 h
all patients with cancer-associated hypercalcaemia should receive treatment with bisphosphonates since the 'first line' therapy (above) cannot be continued indefinitely nor is it without risk. Further, even if the 'first line' therapy has been effective, it is a virtual certainty that the hypercalcaemia will recur in the patient with hypercalcaemia of malignancy. Use of bisphosphonates in such circumstances, then, becomes both therapeutic and preventative
In extreme cases of primary hyperparathyroidism, removal of the parathyroid gland after surgical neck exploration is the only way to avoid death. The diagnostic program should be performed within hours, in parallel with measures to lower serum calcium. Treatment of choice for acutely lowering calcium is extensive hydration and calcitonin, as well as bisphosphonates (which have effect on calcium levels after one or two days).
Hypercalcemia in animals
Research has led to a better understanding of hypercalcemia in non-human animals. Often the causes of hypercalcemia have a correlation to the environment in which the organisms live. Hypercalcemia in house pets is typically due to disease, but other cases can be due to accidental ingestion plants or chemicals in the home. Outdoor animals commonly develop hypercalcemia through vitamin B toxicity from wild plants within their environments.
In certain outdoor environments, animals such as horses, pigs, cattle, and sheep experience hypercalcemia commonly. In southern Brazil and Mattewara India, approximately 17 percent of sheep are affected, with 60 percent of these cases being fatal. Many cases are also documented in Argentina, Papua-New Guinea, Jamaica, Hawaii, and Bavaria. These cases of hypercalcemeia are usually caused by ingesting Trisetum flavescens before it has dried out. Once Trisetum flavescens is dried out, the toxicity of it is diminished. Other plants causing hypercalcemia are Cestrum diurnum, Nierembergia veitchii, Solanum esuriale, Solanum torvum, and Solanum malacoxylon. These plants contain calcitrol or similar substances that cause rises in calcium ion levels. Hypercalcemia is most common in grazing lands at altitudes above 1500 meters where growth of plants like Trisetum flavescens is favorable. Even if small amounts are ingested over long periods of time, the prolonged high levels of calcium ions have large negative effects on the animals. The issues these animals experience are muscle weakness, and calcification of blood vessels, heart valves, liver, kidneys, and other soft tissues, which eventually can lead to death.
^Tierney, Lawrence M.; McPhee, Stephen J.; Papadakis, Maxine A. (2006). Current Medical Diagnosis and Treatment 2007 (Current Medical Diagnosis and Treatment). McGraw-Hill Professional. p. 901. ISBN0-07-147247-9.
^ abcdZiegler R (February 2001). "Hypercalcemic crisis". J. Am. Soc. Nephrol. 12 Suppl 17: S3–9. PMID11251025.
^Page 394 in: Roenn, Jamie H. Von; Ann Berger; Shuster, John W. (2007). Principles and practice of palliative care and supportive oncology. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN0-7817-9595-8.
^ abcdeHypercalcemia in Dogs and Cats Peterson DVM, DACVIM. M. E., July 2013. Hypercalcemia in Dogs and Cats. The Merck Veternary Manual. Merck Sharp & Dohme, Whitehouse Station, NJ, USA.
^ abcdefghijEnzootic Calcinosis Gruenberg MS, PhD, DECAR DECBHM. W.G., April 2014. Enzootic Calcinosis. The Merck Veternary Manual. Merck Sharp & Dohme, Whitehouse Station, NJ, USA.
^ abcdTopical Agents (Toxicity) Khan DVM, MS, PhD, DABVT, S.A., March 2012. Topical Agents (Toxicity). The Merck Veternary Manual. Merck Sharp & Dohme, Whitehouse Station, NJ, USA.