Calcium and phosphorus

Other actions of estrogen include fluid retention, protein anabolism, thinning of the cervical mucus, and the inhibition or facilitation of ovulation. Estrogens contribute to the conservation of calcium and phosphorus, the growth of pubic and axillary hair, and pigmentation of the breast nipples and genitals. Estrogens also stimulate contraction of the fallopian tubes (which promotes movement of the ovum), modify the physical and chemical properties of the cervical mucus, and restore the endometrium after menstruation. 

Lough, S., Rivera, J. and Comar, C.L. 1963 Retention of strontium, calcium, and phosphorus in human infants. Proceedings of the Society of Experimental Biological Medicine 112 613-636. 

The management of secondary hyperparathyroidism involves correction of serum calcium and phosphorus levels, and decreasing parathyroid hormone secretion. 

As renal function declines in patients with CKD, decreased phosphorus excretion disrupts the balance of calcium and phosphorus homeostasis. 0 The parathyroid glands release PTH in response to decreased serum calcium and increased serum phosphorus levels. The actions of PTH include ... 

Uhlig K, Sarnak MJ, Singh AK. New approaches to the treatment of calcium and phosphorus abnormalities in patients on hemodialysis. Curr Opin Nephrol Hypertens 2001 10 793-798. 

However, results obtained by Koo et al. (1991) indicate that low to moderate lead exposure (average lifetime PbB level range of 4.9-23.6 pg/dL, geometric mean of 9.8 pg/dL, n=105) in young children with adequate nutritional status, particularly with respect to calcium, phosphorus, and vitamin D, has no effect on vitamin D metabolism, calcium and phosphorus homeostasis, or bone mineral content. The authors attribute the difference in results from those other studies to the fact that the children in their study had lower PbB levels (only 5 children had PbB levels >60 pg/dL and all 105 children had average lifetime PbB levels <45 pg/dL at the time of assessment) and had adequate dietary intakes of calcium, phosphorus, and vitamin D. They concluded that the effects of lead on vitamin D metabolism observed in previous studies may, therefore, only be apparent in children with chronic nutritional deficiency and chronically elevated PbB levels. Similar conclusions were reached by IPCS (1995) after review of the epidemiological data. 

It has also been demonstrated in animals that lead blocks the intestinal responses to vitamin D and its metabolites (Smith et al. 1981). Dietary concentrations of lead in combination with a low phosphorus or a low calcium diet administered to rats suppressed plasma levels of the vitamin D metabolite, 1,25-dihydroxycholecaliferol, while dietary intakes rich in calcium and phosphorus protected against this effect (Smith et al. 1981). Thus, animals fed a diet high in calcium or phosphorus appear to be less susceptible to the effects of lead, because of hindered tissue accumulation of lead. 

Blake KCH, Mann M. 1983. Effect of calcium and phosphorus on the gastrointestinal absorption of 203Pbinman. Environ Res 30 188-194. 

Quarterman J, Morrison JN. 1975. The effects of dietary calcium and phosphorus on the retention and excretion of lead in rats. Br J Nutr 34 351-362. 

Chandler, P. T. and Cragle, R. G. (1962). Gastrointestinal sites of absorption and endogenous secretion of calcium and phosphorus in dairy calves, Proc. Soc. Exp. Biol. Med. Ill, 431. 

Calcitonin is a polypeptide hormone that (along with PTH and the vitamin D derivative, 1,25-dihydroxycholecalciferol) plays a central role in regulating serum ionized calcium (Ca2+) and inorganic phosphate (Pi) levels. The adult human body contains up to 2 kg of calcium, of which 98 per cent is present in the skeleton (i.e. bone). Up to 85 per cent of the 1 kg of phosphorus present in the body is also found in the skeleton (the so-called mineral fraction of bone is largely composed of Ca3(P04)2, which acts as a body reservoir for both calcium and phosphorus). Calcium concentrations in human serum approximate to 0.1 mg ml-1 and are regulated very tightly (serum phosphate levels are more variable). 

A complete physical examination and laboratory analysis are needed to rule out secondary causes and to assess kyphosis and back pain. Laboratory testing may include complete blood count, liver function tests, creatinine, urea nitrogen, calcium, phosphorus, alkaline phosphatase, albumin, thyroid-stimulating hormone, free testosterone, 25-hydroxyvitamin D, and 24-hour urine concentrations of calcium and phosphorus. Urine or serum biomarkers (e.g., cross-linked N-telopeptides of type 1 collagen, osteocalcin) are sometimes used. 

Precipitation of calcium and phosphorus is a common interaction that is potentially life-threatening. 

See Chap. 52, Disorders of Sodium and Water Homeostasis, authored by James D. Coyle and Melanie S. Joy Chap. 53, Disorders of Calcium and Phosphorus Homeostasis, authored by Amy Barton Pai, Mark Rohrscheib, and Melanie S. Joy and Chap. 54, Disorders of Potassium and Magnesium Homeostasis, authored by Donald F. Brophy and Todd W. B. Gehr, for a more detailed discussion of this topic... 

Bone is very sensitive to dietary factors such as the amount of calcium present in the diet and the availability of that calcium when all other nutrients are present in adequate amounts (46, 47). This is especially true of the growing animal which is utilized in most bioavailability studies. Adult animals, however, may also be used. Krook et al (48) caused osteoporosis in adult dogs in 42 weeks by feeding a low-calcium high-phosphorus diet. The bones were radiologically normal after 28 weeks of calcium repletion (48). The ash contents of the vertebral bones of these dogs were much more responsive to dietary calcium and phosphorus manipulation than were the humeri and femora (48). 

Figure 1. Total amounts and rate of accretion of calcium and phosphorus in the body of the human fetus with gestation. (Reproduced with permission from Ref. 1. Copyright 1965 W. B. Saunders Company.)...

Meat consumption was accompanied by more sulfate output in the urine. This agrees with earlier feeding studies in which animals were fed any of several fixed acids which had been reported to result in increased calcium loss (13, 17). Feeding hydrochloric acid, Goto (17)showed that calcium carbonate was simultaneously lost from the bones of rabbits. A similar conclusion was drawn by Steenbock, et al. (13) who demonstrated a loss of both calcium and phosphorus mediated by hydrochloric acid. These data were consistent with the sulfate infused dog. In the dog, Walzer and Browder (15) showed that sulfate feeding increased calcium losses along with sulfate loss. This confirmed results that Lamb and Evvard (32) reported for the Pig-... 

Effect of Varying Calcium and Phosphorus Content in Animal or Plant Protein-Based Diets... 

Although much attention has been directed toward the relationship between calcium intake and osteoporosis, little consideration has been given to the possible influence of dietary phosphorus on the development of this disease in either man or animals. In a study designed to determine the optimal concentration of calcium and phosphorus in the diet of adult mice, aging animals were found to undergo a greater loss of bone when the Ca/P ratio was 1 1 than... 

Meat and such high protein plant foods as soy are excellent sources of phosphorus as well as protein. The phosphorus in meat is readily absorbed from the gastrointestinal tract however, much of the phosphorus in plant products is in a bound form which may inhibit the absorption of calcium as well as phosphorus. This study was designed to determine the effect of different levels of calcium and phosphorus with plant protein or animal protein on bone breaking strength and calcium and phosphorus utilization of weanling mice. 

Composition of calcium and phosphorus deficient mineral mix from TEKLAD ( 170913) is given in Table III. 

Table IV. Summary of Effects of Alterations in Dietary Protein and Calcium and Phosphorus Sources in Diets...

Mean fecal calcium loss at high levels of calcium intake was 75.0 mg and at low calcium intake was 16.0 mg. Mean calcium and phosphorus levels are illustrated in Figure 6. Orthogonal contrast analysis indicated that the level of calcium in the ration was the only significant source of difference in the data. 

Figure 6. The effect of different ration levels of calcium (Ca = 0.3% and Ca2 = 1.2%) and phosphorus (P1 = 0.3% and P2 = 1.2%) on fecal calcium and phosphorus in mice fed soy (S) or egg white (E) diets. Top Main effect, ca. P < 0.0001. Bottom P-protein interaction P < 0.0001.

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