Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia. Those with a mild increase that has developed slowly typically have no symptoms. In those with greater levels or rapid onset, symptoms may include abdominal pain, bone pain, confusion, depression, weakness, kidney stones or an abnormal heart rhythm including cardiac arrest.Most outpatient cases are due to primary hyperparathyroidism and inpatient cases due to cancer. Other causes of hypercalcemia include sarcoidosis, tuberculosis, Paget disease, multiple endocrine neoplasia (MEN), vitamin D toxicity, familial hypocalciuric hypercalcaemia and certain medications such as lithium and hydrochlorothiazide. Diagnosis should generally include either a corrected calcium or ionized calcium level and be confirmed after a week. Specific changes, such as a shortened QT interval and prolonged PR interval, may be seen on an electrocardiogram (ECG).Treatment may include intravenous fluids, furosemide, calcitonin, intravenous bisphosphonate, in addition to treating the underlying cause. The evidence for furosemide use, however, is poor. In those with very high levels, hospitalization may be required. Haemodialysis may be used in those who do not respond to other treatments. In those with vitamin D toxicity, steroids may be useful. Hypercalcemia is relatively common. Primary hyperparathyroidism occurs in 1–7 per 1,000 people, and hypercalcaemia occurs in about 2.7% of those with cancer. Signs and symptoms
The neuromuscular symptoms of hypercalcaemia are caused by a negative bathmotropic effect due to the increased interaction of calcium with sodium channels.
Bethanechol is a parasympathomimetic choline carbamate that selectively stimulates muscarinic receptors without any effect on nicotinic receptors. Unlike acetylcholine, bethanechol is not hydrolyzed by cholinesterase and will therefore have a long duration of action. Bethanechol is sold under the brand names Duvoid (Roberts), Myotonachol (Glenwood), Urecholine (Merck Frosst) and Urocarb (Hamilton). The name bethanechol refers to its structure as the urethane of beta-methylcholine. Medical uses
Bethanechol alleviates dry mouth and is sometimes given orally or subcutaneously to treat urinary retention resulting from general anesthetic, diabetic neuropathy of the bladder, or a side effect of antidepressants; or to treat gastrointestinal lack of muscular tone. The muscarinic receptors in the bladder and gastrointestinal tract stimulate contraction of the bladder and expulsion of urine, and increased gastrointestinal motility, respectively. Bethanechol should be used to treat these disorders only after mechanical obstruction is ruled out as a possible cause. Its potential benefit in the treatment of cerebral palsy has been investigated.Atropine is given preoperatively to prevent voiding of the bowel/bladder during surgery, Bethanechol is then given postoperatively to revert this action. Contraindications
Use of bethanechol, as well as all other muscarinic receptor agonists, is contraindicated in patients with asthma, coronary insufficiency, peptic ulcers, intestinal obstruction and hyperthyroidism. The parasympathomimetic action of this drug will exacerbate the symptoms of these disorders. References
External links
"Bethanechol". Drug Information Portal. U.S. National Library of Medicine.