|
Hypercalcaemia (British English) or hypercalcemia (American English) is an elevated calcium (Ca2+) level in the blood. (Normal range: 9–10.5 mg/dL or 2.2–2.5 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. ==Signs and symptoms== 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" * Stones (renal or biliary) * Bones (bone pain) * Groans (abdominal pain, nausea and vomiting) * Thrones (polyuria - also looks like Osborn wave on ECG) * Psychiatric overtones (Depression 30–40%, anxiety, cognitive dysfunction, insomnia, coma) Other symptoms can include fatigue, anorexia, and pancreatitis. Limbus sign seen in eye due to hypercalcemia. Hypercalcemia has a negative chronotropic effect (decrease in heart rate), and a positive inotropic effect (increase in contractility). Abnormal heart rhythms can also result, and ECG findings of a short QT interval〔http://lifeinthefastlane.com/ecg-library/basics/hypercalcaemia/〕 suggest hypercalcaemia. Significant hypercalcaemia can cause ECG changes mimicking an acute myocardial infarction. Hypercalcaemia has also been known to cause an ECG finding mimicking hypothermia, known as an Osborn wave.〔Serafi S, Vliek C, Taremi M (2011) "Osborn waves in a hypothermic patient" The Journal of Community Hospital Internal Medicine Perspectives http://www.jchimp.net/index.php/jchimp/article/view/10742/html〕 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hypercalcaemia」の詳細全文を読む スポンサード リンク
|