Serum calcium, lowering

Natelson, S., Pincus, J. B., and Rannazzisi, G., Dynamic control of calcium, phosphate, citrate, and glucose levels in blood serum. Clin. Chem. 9, 31-62 (1963). Natelson, S., Pincus, J. B., and Rannazzisi, G., A rabbit serum calcium lowering factor from the pituitary. Clin. Ckem. 9, 631-636 (1963). 

Parathyroidectomy is a treatment of last resort for sHPT, but should be considered in patients with persistently elevated iPTH levels above 800 pg/mL (800 ng/L) that is refractory to medical therapy to lower serum calcium and/or phosphorus levels.39 A portion or all of the parathyroid tissue may be removed, and in some cases a portion of the parathyroid tissue may be transplanted into another site, usually the forearm. Bone turnover can be disrupted in patients undergoing parathyroidectomy whereby bone production outweighs bone resorption. The syndrome, known as hungry bone syndrome, is characterized by excessive uptake of calcium, phosphorus, and magnesium for bone production, leading to hypocalcemia, hypophosphatemia, and hypomagnesemia. Serum ionized calcium levels should be monitored frequently (every 4 to 6 hours for the first 48 to 72 hours) in patients receiving a parathyroidectomy. Calcium supplementation is usually necessary, administered IV initially, then orally (with vitamin D supplementation) once normal calcium levels are attained for several weeks to months after the procedure. 

Diets were fed to 6-week-old rats for 6 weeks. Ash content of tibia and serum calcium were lower on the diets containing oxalate. Four out of six rats on the sodium oxalate diet died after the fourth week, and all of the rats lost weight on this diet. 

Hypomagnesemia - Magnesium sulfate is used as replacement therapy in magnesium deficiency especially in acute hypomagnesemia accompanied by signs of tetany similar to those observed in hypocalcemia. In such cases, the serum magnesium (Mg++) level is usually below the lower limit of normal (1.5 to 2.5 or 3 mEq/L) and the serum calcium (Ca++) level is normal (4.3 to 5.3 mEq/L) or elevated. 

Hypomagnesemia Loop diuretics increase the urinary excretion of magnesium. Hypocalcemia Serum calcium levels may be lowered (rare cases of tetany have occurred). 

Bone and calcium Lower serum Ca + Inhibition of vitamin D function on intestinal Ca + absorption... 

Mithramycin (also known as MIT and plicamy-cin) is an antibiotic that binds to DNA to regulate transcription. It attaches to specific regions of DNA that are rich in guanine and cytosine. It appears to lower serum calcium concentrations by blocking the hypercalcemic action of Vitamin D. After IV administration about 25% of the drug is excreted in the urine after 2 hours, and 40% after 15 hours. The main indications are treatment of testicular tumors and control of hypercalcemia and hypercalciuria. 

Plicamycin (mithramycin, Mithracin) is one of the chro-momycin group of antibiotics produced by Streptomyces tanashiensis. Plicamycin binds to DNA and inhibits transcription. It also inhibits resorption of bone by osteoblasts, thus lowering serum calcium levels. Very little is known about its distribution, metabolism, and excretion. Because of its severe toxicity, plicamycin has limited clinical utility. The major indication for plicamycin therapy is in the treatment of life-threatening hypercalcemia associated with malignancy. Plicamycin also can be used in the palliative therapy of metastatic testicular carcinoma when all other known active drugs have failed. 

A 36-year-old white woman is noted to have a 1.5-cm nodule in the right lower lobe of her thyroid on routine examination. Her thyroid functions are normal and a uptake and scan of the thyroid produce normal findings. Her serum calcium levels were determined to be 14 mg/dL (normal levels 9 to 10.3 mg/dL). What is the most likely diagnosis ... 

Mechanism of Action A bisphosphate that binds to bone and inhibits osteoclast-mediated calcium resorption. Therapeutic Effect Lowers serum calcium concentrations. 

Mechanism of Action An antibiotic that forms complexes with DNA, inhibiting DNA-directed RNA synthesis. May inhibit parathyroid hormone effect on osteoclasts and inhibit bone resorption. TherapeuticEffect Lowers serum calcium and phosphate levels. Blocks hypercalcemic action of vitamin Dand action of parathyroid hormone. Decreases serum calcium. 

Because of its toxicity, plicamycin (mithramycin) is not the drug of first choice for the treatment of hypercalcemia. However, when other forms of therapy fail, 25-50 mcg/kg given intravenously usually lowers serum calcium substantially within 24-48 hours. This effect can last several days. This dose can be repeated as necessary. The most dangerous toxic effect is sudden thrombocytopenia followed by hemorrhage. Hepatic and renal toxicity can also occur. Hypocalcemia, nausea, and vomiting may limit therapy. Use of this drug must be accompanied by careful monitoring of platelet counts, liver and kidney function, and serum calcium levels. 

Calcitonin is a peptide hormone produced in the thyroid gland that serves to lower serum calcium and phosphate levels by inhibiting bone resorption. Calcitonin has been used in the treatment of a variety of diseases, such as primary hyperparathyroidism, Paget s disease, and postmenopausal osteoporosis [99,100]. Salmon calcitonin has a longer half-life than human calcitonin. Salmon calcitonin, 3.6 kDa, is available as a nasal formulation that contains only benzalkonium chloride as a preservative, without an absorption enhancer, and as a parenteral product for injection. The direct effect of benzalkonium chloride on the nasal mucosa is under... 

Aspirin, prostaglandin, and hypercalcemia Certain solid tumors (renal cell carcinoma) cause hypercalcemia, which may be mediated by prostaglandin E2. Taking a high dose of aspirin or another nonsteroidal anti-inflammatory agent will lower the serum-calcium level. 

The principal effects of calcitonin are to lower serum calcium and phosphate by actions on bone and kidney. Calcitonin inhibits osteoclastic bone resorption. Although bone formation is not impaired at first after calcitonin administration, with time both formation and resorption of bone are reduced. Thus, the early hope that calcitonin would prove useful in restoring bone mass has not been realized. In the kidney, calcitonin reduces both calcium and phosphate reabsorption as well as reabsorption of other ions, including sodium, potassium, and magnesium. Tissues other than bone... 

Hypercalcemia causes central nervous system depression, including coma, and is potentially lethal. Its major causes (other than thiazide therapy) are hyperparathyroidism and cancer with or without bone metastases. Less common causes are hypervitaminosis D, sarcoidosis, thyrotoxicosis, milk-alkali syndrome, adrenal insufficiency, and immobilization. With the possible exception of hypervitaminosis D, these latter disorders seldom require emergency lowering of serum calcium. A number of approaches are used to manage the hypercalcemic crisis. 

The increase in serum calcium above the normal range would appear to have been the initial stimulus to the study of this condition. Values up to 18.7 mg/100 ml have been reported (S2), although the usual range of maximum levels is from 12.5 to 15 mg/100 ml. There is, however, good evidence that in the disease entity which we call idiopathic hypercalcemia the serum calcium can be lower than 12.5 mg/100 ml. The disease has been reported in the presence of levels of 11.2 mg/100 ml and 12.0 mg/100 ml (F7, L6). Recovery from idiopathic hypercalcemia is accompanied by a return to within the normal range. It is probably true to say that an elevated serum calcium may be regarded as a diagnostic aid, and it is, of course, implied in the title of the condition. 

A low-calcium diet lowers the serum calcium level in idiopathic hypercalcemia of infancy (B5, F4, F7, Ml, R4, S8). It results in a marked reduction in calcium retention and can convert a strongly positive calcium balance to a less positive or even negative one (F7, Ml). 

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