Serum calcium levels

Figure 8. The effect of different ration levels of calcium (Cai = O.37o and Ca2 = 1.2%) and phosphorus (Pi = 0.37> and P2 = 1.27 ) on mice serum levels. Top Ca-protein interaction P < 0.0007. Bottom Ca-protein interaction P < 0.0197.

Blood samples were centrifuged at 1000 x g for 20 min at 0-4°. Ionized calcium levels were immediately determined in serum and urine samples using a calcium ion-selective electrode (Ionetics, Inc., Costa Mesa, CA) urine volumes were recorded. The remaining serum and urine were aliquoted for various analyses and stored at -40°. Serum insulin was analysed by radioimmunoassay (Amersham Corp., Arlington Heights, IL). Serum levels of total calcium, phosphorus and creatinine as well as urine creatinine were determined by colorimetric procedures using an automated analyzer (Centrifichem, Baker Instruments Corp., Pleasantville, NY). Glomerular filtration rates (GFR) were calculated from serum and urine creatinine data GFR = urine creatinine/serum creatinine. 

The effects of varying either the calcium or phosphorus level in conjunction with a high beef meal on the urinary calcium excretion of men are shown in Table IV. Urinary calcium excretion (total and ionized) was significantly elevated (P < 0.005) when the high protein beef meal contained 466 mg rather than 166 mg calcium. Increasing the phosphorus level from 308 mg to 700 mg in the high beef meal reduced both total and ionized calcium excretion in the urine, but the response was not statistically significant. Serum levels of calcium (ionized and total) and phosphorus were within normal limits and were unaffected by any of the dietary treatments. 

Results. Table VI gives the serum levels of calcium (total and ionized) and phosphorus. Serum ionized calcium, which ranged from 33% to 36% of total serum calcium, did not respond postprandially to any of the diets consumed. 

When compared to the basal meal (no protein meal), total serum calcium levels were significantly elevated following the ingestion of either cottage cheese meal (P < 0.05). Feeding 15 g of protein from beef also elevated total serum calcium above levels obtained with the basal diet (P < 0.05). Total serum calcium responded similarly to meals containing 0 or 45 g of protein from either beef or soy. 

Discussion. In this study of postmenopausal women, serum levels of ionized calcium were unaffected by meal consumption. Levels of total calcium, however, were elevated following meals containing 15 g of protein from either cottage cheese or beef, or 45 g of protein from cottage cheese. Serum total calcium was not affected by diet in the study with men nor in the study reported by Allen et al. using men and women (16). 

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. 

Monitoring Carefully monitor standard hypercalcemia-related metabolic parameters, such as serum levels of calcium, phosphate, magnesium, and potassium following pamidronate and zoledronic acid initiation. Also, closely monitor electrolytes, creatinine as well as CBC, differential and hematocrit/hemoglobin. Carefully monitor patients who have preexisting anemia, leukopenia or thrombocytopenia in the first 2 weeks following treatment. 

Drugs that may interact with foscarnet include nephrotoxic drugs (eg, aminoglycosides, amphotericin B, IV pentamidine), pentamidine, and zidovudine. Foscarnet decreases serum levels of ionized calcium. Exercise particular caution when other drugs known to influence serum calcium levels are used concurrently. 

A) Hyperparathyroidism serum calcium, PTH level, and ultrasound of the thyroid should be obtained. 

Platelet count, and serum levels of inorganic phosphate, calcium, total and LDL cholesterol, and protein... 

Adjusted serum calcium, serum alkaline phosphatase, osteocalcin, and urinary hy-droxyproline levels to assess the effectiveness of tiludronate... 

After exposure for 12 days, sexually mature females had significant declines in plasma levels of reproductive and metabolic hormones, and sexually mature males had decreased spermatocytes and selective cell loss in pituitary gland Exposure to 10 or 20 pg/L caused a reduction in serum calcium to levels insufficient for the production of exogenous yolk this was not observed in the 30 pg/L group... 

Abnormal Serum Calcium Phosphate Levels HYPERCALCEMIA... 

Net effect on serum levels Serum calcium increased, serum phosphate decreased Serum calcium and phosphate both increased... 

Calcifediol (25[OH]D3) may also be used to advantage. Calcifediol is less effective than calcitriol in stimulating intestinal calcium transport, so that hypercalcemia is less of a problem with calcifediol. Like dihydrotachysterol, calcifediol requires several weeks to restore normocalcemia in hypocalcemic individuals with chronic renal failure. Presumably because of the reduced ability of the diseased kidney to metabolize calcifediol to more active metabolites, high doses (50-100 Pg daily) must be given to achieve the supraphysiologic serum levels required for therapeutic effectiveness. 

In mild forms of malabsorption, vitamin D (25,000-50,000 units three times per week) should suffice to raise serum levels of 25(OH)D into the normal range. Many patients with severe disease do not respond to vitamin D. Clinical experience with the other metabolites is limited, but both calcitriol and calcifediol have been used successfully in doses similar to those recommended for treatment of renal osteodystrophy. Theoretically, calcifediol should be the drug of choice under these conditions, since no impairment of the renal metabolism of 25(OH)D to l,25(OH)2D and 24,25(OH)2D exists in these patients. Both calcitriol and 24,25(OH)2D may be of importance in reversing the bone disease. As in the other diseases discussed, treatment of intestinal osteodystrophy with vitamin D and its metabolites should be accompanied by appropriate dietary calcium supplementation and monitoring of serum calcium and phosphate levels. 

In a study of 71 workers exposed to airborne white phosphorus for intermediate or chronic durations, 4.5% and 44%, respectively, developed phossy jaw (Ward 1928). Forty-eight male workers with exposure to white phosphorus ranging from 1 to 17 years were found to be normal and healthy with regards to many parameters, including serum levels of calcium and phosphorus, and bone density none of the men developed phossy jaw (Hughes et al. 1962). 

Vitamin D that is taken up by the fiver is converted to 25-hydroxyvitamin D by a microsomal hydroxylase (Fig. 30-3). 25-Hydroxyvitamin D is the main circulating form of vitamin D in the serum and the best indicator of vitamin D status. Normal serum levels are 14-60 ng/mL (35-150 nmol/L). When serum calcium concentrations decline, 25-hydroxyvitamin D is converted to 1,25-dihydroxyvitmin D by la-hydroxylase, a mixed-function oxidase that is located in the inner mitochondrial membrane in kidney tissue and whose expression is regulated by parathyroid hormone (PTH). The main function of 1,25-dihydroxyvitamin D is to increase the intestinal absorption of dietary calcium and phosphorus. When serum concentrations of calcium and phosphorus are normal or when large doses of vitamin D are administered, 25-hydroxyvitamin D is metabolized to 24,25-dihydroxyvitamin D in the renal... 

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