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IT HAS been known for a long time that estrogens play an important role in calcium metabolism in the bird. Due to the enormous amount of calcium excreted during the period of egg shell formation it is likely that the hen requires a special mechanism to control calcium balance at that time. Riddle and Reinhart (1926) showed that the blood calcium rises in the pigeon prior to egg shell formation and is maintained until shell formation is completed. Similarly a hypercalcemia has been shown in the laying hen (Parhon, 1926; Hughes, Titus and Smits, 1927). Treatment with estrogens causes a marked rise in the blood calcium of the pigeon (Riddle and Dotti, 1936; Pfeiffer and Gardner, 1938), the chicken (Altman and Hutt, 1938; Zondek and Marx, 1939; Landauer et al., 1939) the duck (Landauer et al., 1941) and the sparrow (Pfeiffer et al., 1940). Similar results are obtained in the . . .

1. Bone trabeculae are easily depleted by the prolonged administration of parathormone, long continued negative calcium balance and growth. 2. A long continued high calcium diet results in a rapid accumulation of the trabeculae. 3. Alizarin red, as has previously been shown in the literature, is deposited in newly formed bone. Its use has made clear that easily mobilizable calcium is not deposited in the shafts of adult animals, but in the trabeculae of bone. 4. The bone trabeculae therefore serve as the storehouse of readily available calcium. 5. The shafts have a slow progressive exchange of inorganic salts and are not influenced except in the case of unusual body demands. 6. It is suggested that the absence of trabeculae in premature infants and their depletion at the end of 4 months in a normal baby might well be an etiological factor in rickets. 7. In our observations, parathormone administration to growing or adult cats has been without effect. 8. Daily injections of parathormone in growing rats results in an increased number of trabeculae and smaller bones.

BENNION and Warren (1933) and Warren and Schnepel (1940) reported that shell thickness is reduced markedly if hens are subjected to high environmental temperatures. Their experiments further suggested that the depressing effect of high temperature is accentuated by high humidity. The mechanism or mechanisms which cause poor shell quality at high air temperatures are still not definitely established. Conrad (1939) found that blood calcium levels were reduced at high environmental temperatures. From this evidence Warren and Schnepel (1940) concluded that: “The decrease in shell thickness when the birds are subjected to high temperatures is probably due to a reduction in calcium content of the blood.” Warren and Schnepel (1940) also reported that hens kept at 95°F. consumed about 26% less feed than hens kept at 60°F. It is possible that this reduction of feed intake is at least partially responsible for the poor shell quality at high air temperatures. Finally, …

1. Nous avons essaye de mettre au point une methode nous permettant de dresser des bilans calciques valables. L'experience acquise nous a demontre l'interet qui s'attache a notre facon de proceder. 2. L'etude du bilan calcique nous semble indiquee pour deceler l'hyperparathyroidie lorsque celle-ci echappe, ce qui est frequent, a l'examen simple du calcium et du phosphore sanguin. 3. Un bilan calcique franchement negatif etablit alors la nature hyperparathyroidienne de l'affection en cause. 4. Dans la lithiase urinaire, l'hyperparathyroidie relevee par l'etude des bilans calciques nous parait apres une experience de 7 cas frequente (4 fois sur 7), mais non constante. 5. Dans la polyathrite chronique deformante et ankylosante, nous avons trouve sur 4 cas, 2 bilans franchement positifs; 1 pratiquement normal (9,2%) et 1 legerement negatif (−17,2%). 6. Des bilans plus ou moins positifs ont ete observes, dans deux cas de maladie de Raynaud et dans la maladie de Lobstein. 7. Toute une serie d'autres cas, assez disparates ont ete etudies avec des bilans tontot negatifs, tantot positifs, tantot pratiquement normaux. 8. Il est trop tot pour en tirer une conclusion definitive; mais des maintement nous avons voulu attirer l'attention sur une methode d'exploration de la fonction parathyroidienne qui, malgre la complexite des dosages qu'elle comporte, parait meriter d'etre essayee sur une plus vaste echelle.

Two patients with vitamin D resistant rickets respond to a high phosphorus intake by a positive calcium balance. The response to a calcium infusion suggests a parathyroid effect on phosphaturia but th

Glucocorticoids tend to lower the intestinal absorption of calcium, leading to a negative calcium balance. A 7-year-old girl with hypoparathyroidism was maintained as normocalcaemic on 1-alpha-hydroxyvitamin D3 (1 alpha D3) and calcium gluconate lactate. During an episode of aplastic anaemia she was treated with prednisolone, with a subsequent dramatic fall of serum calcium despite 1 alpha D3 treatment and serum 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in the high-normal range. Glucocorticoids seem to have interfered directly with cellular events responsible for intestinal absorption of calcium.

Patients put at bedrest for medical reasons lose 1-2% of spinal bone mineral per week. Losses of this magnitude during even short-term space flights of a few months would pose a serious limitation and require countermeasures. The spinal bone mineral (L2-L4) was determined in 6 healthy males (precision = 2%) before and after 5 weeks of complete bed rest. Only one individual had a significant loss (3%) and the -0.9% mean change for the 6, was not significant (P = 0.06). The average negative calcium balance during the 5 weeks was 4 g or 0.36% of total body calcium, similar to that reported in other bed-rest studies. Spinal bone loss, however, in healthy bed-rested males is significantly less than reported for bed-rested patients, suggesting that a large loss of spinal bone mineral does not occur during space flight missions lasting 5 weeks or less.

An experiment was conducted on twelve cows for six weeks. These animals were further divided into four groups each having three animals. The four treatments were concentrate mixture with green grass (T1), concentrate mixture without green grass (T2), ground-nut cake with green grass (T3), and ground-nut cake without green grass (T4). The DCP requirements were met as per feeding standards recommended by Sen and Ray. At the end of each period, metabolism trials were conducted by conventional method. Nitrogen, phosphorus and calcium balance were positiv ein all the groups of cows. Treatment T1 and T2 have increased the milk yield while reverse was true for treatment T3 and T4. Der Einflus der Tutterung auf Trockenmasseaufnahme, Verdaulichkeit und Nahrstoffgleichgewicht bei Krankrejkuhen Uber einen Zeitraum von 6 Wochen wurde an 12 Kuhen folgendes Experiment durchgefuhrt. Die Tiere wurden in 4 Gruppen zu je 3 Tieren eingeteilt. Vier Futterungsmethoden wurden angewandt: Mischkonzentrat mit grunem Gras (T1), Mischkonzentrat ohne grunes Gras (T2), Erdnuskuchen mit grunem Gras (T3) und Erdnuskuchen ohne grunes Gras (T4). Die von Sen und Ray empfohlenen Futterungsstandards wurden eingehalten. Am Ende jedes Abschnitts wurden Stoffwechseluntersuchungen mit konventioneller Methode durchgefuhrt. Bei allen Tiergruppen bestand ein positives Gleichgewicht von Stickstoff, Phosphor und Calcium. Futterungsmethode 1 und 2 erhohten den Milchertrag, wahrend fur Methode 3 und 4 das Gegenteil der Fall war.

Clomiphene citrate, a mixed estrogen agonist-antagonist, protects mature ovariectomized breeder rats from changes in total body calcium and from deterioration of femur structure. Over 6 months, mature ovariectomized rats took up calcium at the rate of 0.7 +/- 0.5 mg/day, while normal controls gained 2.5 +/- 0.7 mg/day (mean +/- SEM) as measured by whole body neutron activation analysis. Injections of clomiphene (20 mg/kg/week) kept ovariectomized rats in positive calcium balance at 2.0 +/- 0.5 mg/day. Reductions in total femur calcium content, cortical thickness, and visible trabeculae of femurs in ovariectomized animals were prevented by chronic clomiphene administration. These results in animals suggest a possible new line of investigation of the use of antiestrogenic drugs as therapeutic agents for hormone-dependent osteoporosis in animals and humans.

Plasma and urinary levels of calcium and phosphorus have been determined in 39 healthy premenopausal women, 28 post-menapausal women in whom the menopause had been natural, and 51 women who had undergone bilateral salpingo-oophorec- tomy. The levels were increased after the menopause, particularly where this bad been artificial. It is suggested that loss of œ strogenic activity at the menopause results in increased bone resorption. It is not clear, however, whether the resultant negative calcium balance is the cause of or the result of osteoporosis in post-menopausal women.

The main contributions of bony skeletal elements are to the mechanical functions of the bone. In addition bone acts as a depot of chemical substances that are integrated into the metabolic process, such as the systemic calcium balance.

AFBF is an hemodiafiltration which utilizes a buffer-free dialysate and hypertonic sodium bicarbonate as replacement fluid (1). It allows to overcome the side effects of acetate-dialysis as well as the clinical and technical problems of bicarbonate-dialysis such as bacterial contamination of dialysate and toilsome maintenance. The aim of this study is to evaluate the “adequacy” of AFBF as regards depuration and electrolytes balance.

Eight young adult males were subjects in a 51-day metabolic study conducted to examine the effects of level of protein and of phosphorus intake on urinary calcium and calcium balance. Two levels of protein (50-150 g) were given at each of two levels of phosphorus intake (1,010 and 2,525 mg). Dietary calcium and magnesium were maintained at 500 and 350 mg, respectively. Raising the protein intake from 50 to 150 g caused a calciuresis at both phosphorus intakes, but the actual increase in urinary calcium was 71 mg/day greater at the low than at the high phosphorus intake and calcium balance was changed from 24 to -116 mg/day at the low phosphorus intake and from 8 to -25 mg/day at the high. When the phosphorus intake was raised, urinary calcium decreased from 156 to 93 mg/day at the low protein intake and from 334 to 200 mg/day at the high protein intake and the markedly negative calcium balance found at the high protein intake was greatly improved. Simultaneous increases in protein and phosphorus intakes caused a 28% increase in urinary calcium whereas the increase in protein intake alone caused a 115% increase.

Eighteen postmenopausal osteoporotic (PMO) women on placebo therapy were followed for 1 year. Serial measurements of calcium balance and kinetics, bone histomorphometry, photon absorptiometry, and radiogrammetry were obtained. Few significant changes in balance and kinetics or bone histology were seen in these women over time. Photon absorptiometry and radiogrammetry of the femoral cortex showed a significant annual bone loss however. When compared with premenopausal and healthy postmenopausal women, the annual bone loss in those with PMO was significantly greater. The ability of balance studies, photon absorptiometry, and radiogrammetry to predict the magnitude of this bone loss was similar. Finally, there was an illustration of the use of the estimated variance provided by this study for estimating sample size for future studies.

The results of biomedical investigations carried out in the U.S.S.R. manned space missions are discussed. Their basic result is well-documented evidence that man can perform space flights of long duration. The investigations have demonstrated no direct correlation between inflight or postflight physiological reactions of crewmembers and flight duration. In all likelihood, this can be attributed to the fact that special exercises done inflight efficiently prevented adverse effects of weightlessness. However, human reactions to weightlessness need further study. They include negative calcium balance and anemia as well as vestibulo-autonomic disorders shown by crewmembers at early stages of weightlessness. Attention should be given to psychological, social-psychological and ethical problems that may also limit further increase in flight duration.

The observation that diets rich in cereals produced rickets in puppies if they were also fed inadequate amounts of a fat-soluble vitamin was made by Mel-lanby1 during the First World War. The historical development of the concept that phytate might be involved in this rachitic effect has been set out by Wid-dowson,2 one of the pioneers in this field. The observations were extended to man more than 40 years ago by McCance and co-workers during studies on the nutritional effects of whole-grain bread and oatmeal.3–5 At that time, the deleterious effect of many unrefined foods, particularly cereals, on calcium and iron balances was ascribed to their phytate content. Only recently has fiber itself been implicated, and the concern for the malabsorption of other minerals been extended to include zinc. Much of this older work is still relevant today, and, since these classic studies are often neglected when considering the problem of mineral malabsorption on high-fiber diets, they will be evaluated in this chapter.

Calcitonin was measured in four patients with acute pancreatitis with hypocalcemia. A marked elevation of this hormone was noted in each case and persisted over several days. The peak level of calcitonin preceded the maximum fall in calcium. Among the various factors affecting calcium balance in pancreatitis, calcitonin probably plays an important role.

Along with positive effects of increased fiber in the diet, there have been reports of decreased bioavailability of nutrients. Some nutrients may be bound by fiber and thus rendered unavailable for absorption by the body.

Recent investigations in human and experimental hypertension have characterized previously unrecognized abnormalities of calcium homeostasis. Data from human and animal studies have indicated that adequate dietary calcium intake may be an important determinant for the development of high blood pressure. Since dietary calcium supplementation has been shown to attenuate the hypertension of the spontaneously hypertensive rat (SHR), the present study was undertaken to assess the effect of dietary calcium intake on the blood pressure of the Wistar-Kyoto rat (WKY), the normotensive genetic control for the SHR. One of three levels of dietary calcium was fed to 36 WKYs beginning at eight to 10 weeks of age (WOA) through 34 WOA. Throughout the period of observation, the WKYs stratified inversely with their level os dietary calcium (p less than .001), i.e. rats fed the lowest level of calcium had the highest blood pressure. WKYs on the high calcium diet experienced an attenuation of their blood pressure with increasing age and dietary calcium intake. These salutary blood pressure effects of dietary calcium were independent of growth and urinary sodium excretion of the rats. Serum ionized calcium (Ca++) increased in the high calcium diet WKYs and appeared to be associated with the blood pressure reduction. The results suggest that calcium intake must be assessed in experimental models of hypertension and that the state of calcium balance is a possibly important determinant of blood pressure regulation.

Elevated parathyroid hormone (PTH) concentrations in plasma can be found during pregnancy and are due to a negative calcium balance; however, clinically manifest hyperparathyroidism (HPT) is rare and may remain undiscovered during pregnancy. Only after late hypocalcemic tetany in the newborn the diagnosis becomes apparent.

Normal, healthy adults must be assumed to be in a state of nutritional equilibrium — at least over a period of time. They must be taking in nitrogen, phosphorus, sodium and other elements at the same rate as they are excreting them. For some of these elements, the calculation of a body balance is very difficult, but in the case of calcium it is relatively simple. Discounting dermal losses [which may be quite significant (Charles et al. 1983)], the calcium balance is the difference between the dietary calcium on the one hand and the faecal and urinary calcium on the other.

Studies on the effects of certain blood constituents such as electrolytes, metabolic substrates, and hormones on pathophysiologic phenomena such as hypertension are prompted on the one hand by the theoretical possibility of such effects and on the other by epidemiologic observations which point to correlations.

Fat, phosphorus, and calcium balance studies were performed in normal very low birth weight infants (BW less than or equal to 1,500 g) fed either normal or calcium- and phosphorus-supplemented pooled pasteurized human milk. Calcium and phosphorus supplements were 27 mg/dl and 24.5 mg/dl, respectively, throughout the study. Measured calcium and phosphorus intake in the supplemented group averaged 90 +/- 6 mg/kg/day and 62 mg/kg/day, respectively, compared to 47 +/- 7 mg/kg/day and 24 +/- 6 mg/kg/day in the nonsupplemented group. The percent of fat, calcium, and phosphorus absorption was similar in the two groups: respectively, 71 +/- 23%, 73 +/- 13%, and 93 +/- 2% in the supplemented group compared to 75 +/- 11%, 71 +/- 14%, and 92 +/- 4% in the nonsupplemented group. Calcium and phosphorus retention reached 62 +/- 12 mg/kg/day and 53 +/- 4 mg/kg/day in the supplemented group against 21 +/- 10 mg/kg/day and 21 +/- 5 mg/kg/day in the nonsupplemented group. These data support the notion that calcium, in addition to phosphorus supplementation in pooled human breast milk, improves both calcium and phosphorus retention in preterm infants.

Total body calcium was measured using in vivo neutron activation analysis in 156 patients with rheumatic diseases at six-month intervals. Evidence of seasonal variation was sought by relating deviation from a linear change to the month in which the measurement was made. A cyclic regression fitted to the data had an amplitude of 0.25% but a significance of only P=0.08. The calcium balance studies of Malm (see Scand. J. Clin. Lab. Inv., vol.10, supplement 36, p.1-290, 1958) were re-analysed to quantify the seasonal variation he had demonstrated in one group of men. The deduced variations of body calcium were highly significant, with a phase and amplitude very similar to the regression of the authors' data. Both analyses differed from two previous reports of seasonal variations of part-body bone mineral of much greater amplitude and different phase.

Combined 47Calcium kinetic and calcium balance studies with correction for dermal calcium loss were performed in thirteen patients with primary hyperparathyroidism (PHP), in whom serum bone-Gla-protein (S-BGP) was measured, and in ten matched controls. Dietary calcium was normal in PHP but both net (7.9 +/- 1.4 mmol Ca day-1 in PHP v. 3.5 +/- 0.9 mmol Ca day-1 in normals (mean +/- SE] and true (11.1 +/- 1.6 v. 6.8 +/- 0.9 mmol Ca day-1) intestinal absorbed calcium were enhanced (P less than 0.05). The renal calcium excretion (10.9 +/- 0.8 v. 5.1 +/- 0.4 mmol Ca day-1, P less than 0.001) and the dermal calcium loss (2.5 +/- 0.3 v. 1.5 +/- 0.1 mmol Ca day-1, P less than 0.02) were increased in PHP. Both patients and controls were in a negative calcium balance (P less than 0.01 and P less than 0.001, respectively) without any difference between the groups (P greater than 0.10). Mineralization (12.0 +/- 1.7 v. 4.8 +/- 0.8 mmol Ca day-1, P less than 0.02) and resorption rates (17.6 +/- 2.5 v. 7.9 +/- 0.6 mmol Ca day-1, P less than 0.02) were increased in PHP and S-BGP correlated positively to both variables (r = 0.64, P less than 0.05 and r = 0.62, P less than 0.05, respectively). Serum immunoreactive parathyroid hormone correlated positively to serum calcium (r = 0.69, P less than 0.01) but not to the calcium kinetic data.

Women lose a considerable amount of calcium from the bones after the menopause. The clinical manifestations of this negative calcium balance are fractures, collapse of one or more vertebrae, and reduced body height. Treatment is largely ineffective once the symptoms have set in and preventive treatment, if it exists, should therefore be instituted at the start of the menopause.

Previous studies have indicated the beneficial effects of porcine, salmon and human calcitonin on the clinical and biochemical disturbances in Paget’s disease (BELL et al., 1970; BIJVOET et al., 1968; HADDAD et al., 1970; SHAI et al., 1970; WOODHOUSE et al., 1971).

Urinary adenosine 3′, 5′-monophosphate (cyclic AMP, cAMP) has been determined in 84 males. Two protein-binding assays were used: the method of Gilman and the Amersham assay kit. The results were in close agreement. The excretion of cAMP was not correlated to urinary calcium or to estimated calcium intake.

Bone disease as a complication of gastrectomy was predicted on the basis on their calcium balance studies by Nicolaysen and Ragard [1], who concluded that the negative balance demonstrated in their patients must inevitably have later metabolic consequences.

During Hemodiafiltration (HDF) the kinetics of bicarbonate and calcium involves both a convective loss through the filter into the dialysate and a diffusive uptake from the dialysate (1). A careful study of these phenomena is, therefore, necessary to avoid acid-base and calcium imbalance. Aim of this study was to evaluate the balance of both bicarbonate and calcium through the filter during postdilutional HDF.

It has been known for decades that abnormalities of calcium balance and of calcium-regulating hormones are hallmarks of uremia. This brief review emphasizes recent progress in the field as well as points relating to nutritional management of patients.

Calcium restriction reliably produces osteoporosis in animals, but the impact of dietary calcium on age-related bone loss in man is controversial. The opinion that calcium intake is not clearly related to bone mass or to osteoporosis is well-entrenched in the nutrition literature, and has been influential in setting recommended intakes for the American public. This position rests on the poor correlation between habitual calcium intake and the incidence of osteoporosis in some non-Western countries, and on demonstrations that young men can achieve calcium balance on low intakes. However, such data neglect a variety of factors which determine calcium nutriture. These include the efficiency of mineral utilization, gonadal status, and the effect of dietary protein. It has recently been demonstrated that calcium requirements increase during adult life in women. This increase is attributable in large measure, but not completely, to estrogen deprivation associated with the menopause. In addition, the American diet is abundant in protein, a situation which may be deleterious to bone. Based on the evidence currently available, it is reasonable to propose that adolescent and young women consume one gram of calcium daily, and that this intake be increased to 1500 mg at the time of menopause.

1. Calcium balances and formation rates of new bone measured with an improved tracer technique using 85Sr have been determined simultaneously in 21 patients with idiopathic osteoporosis and vertebral crush fractures. 2. A weak positive association was found between calcium balance and the kinetically measured calcium accretion rate, which is the sum of the true rate of bone formation and various long-term exchange processes. 3. The more negative balances were associated with significantly greater early loss of tracer taken up into bone by ‘accretion’, so that long-term (> 200 day) uptake was reduced. 4. This indicates that patients actively losing bone mineral have lower true rates of bone formation and higher rates of long-term exchange than their fellow patients who are more nearly in calcium equilibrium. 5. No statistically significant association was found between measured rates of bone resorption and calcium balance.

The widespread opinion that both protein and phosphorus cause calcium loss is examined. Controlled human studies show that commonly used complex dietary proteins, which have a high phosphorus content, do not cause calcium loss in adult humans. Similarly, a phosphorus intake of up to 2000 mg/d does not have adverse effects on calcium metabolism; however, the type of phosphate contained in carbonated beverages may not behave in the same manner. In contrast, a diet low in protein and phosphorus may have adverse effects on calcium balance in the elderly. Studies with adults suggest that high protein foods do not cause calcium loss.

Calcium balances were determined in 13 patients during 2--4 3-day periods following both period marking (with carmine) and continuous marking (with polyethylene glycol or chromium). The reliability coefficient for the uncorrected fecal calcium (obtained from period marking) from one period to another was 0.82, whereas it was 0.97 for corrected fecal calcium (determined from recovery of continuous marker in 3-day fecal pools). Thus, the addition of continuous marking yielded a significantly more reliable measure of fecal calcium than obtainable by the use of period marking alone (p < 0.05); the error variance for corrected fecal calcium from one period to another was 3%, whereas it was 18% for uncorrected fecal calcium. It is concluded that a reliable measure of fecal calcium, and hence calcium balance, could be obtained by combined use of continuous and period markers, involving fecal collection over only one 3-day study period (marked by period marker), and correction of fecal calcium for the completeness of fecal collection (determined from continuous fecal marker).

The long-term reproducibility of bone mineral content (BMC) measurements using two identical equipments for two-dimensional fore-arm scanning, was measured in normal persons and aluminium standards (corresponding to normal persons and severely osteopenic patients). The mean coefficient of variation in normal subjects measured for one year was 1.4%. The data were used to estimate that this equipment can measure BMC in osteopenic patients with a long term reproducibility of 1.7%, which is sufficient for use in the clinically relevant range of calcium balance.

Calcium balance studies are time-consuming and tedious to perform. They also require strictly controlled study conditions, namely a constant dietary intake, completeness of collections of excreta, analyses of calcium intake as well as urinary and fecal excretions. These balances have to be determined for relatively long periods of time in order to obtain interpretable data because of the time required for adaptation to a given calcium intake. Another reason for employing long-term balance studies is the fact that passage of minerals, including calcium, through the intestine may be considerably delayed [2,38]. Despite these difficulties and the unavoidable errors inherent in determining calcium balances, the state of calcium metabolism can be quite reliably assessed by determining the intake and excretion of calcium in urine and stool. The loss of calcium in sweat is usually not monitored, and calcium balances must therefore be considered as maximal values.

Pronounced serum phosphate deficiency has been shown to be deleterious when starting parenteral nutrition in severely malnourished patients. The consequences of phosphate deficiency and the need for phosphate supplementation in critically ill patients are not well known. Thirty ICU patients randomized into two groups were studied. The patients received complete parenteral nutrition with and without addition of extra phosphate. The low phosphate group got 7.5 mmol phosphate (from the phospholipids in the fat emulsion) and the high phosphate group got 60–80 mmol phosphate/day. There were no significant differences in serum phosphate or calcium levels between the groups. In the high phosphate group the phosphate balance was positive and calcium balance zero while in the low phosphate group both phosphate and calcium balances were negative. The phosphate content in a standard nutrition programme is not sufficient to create a positive phosphate balance. With the addition of 80 mmol phosphate/day a positive balance was achieved. It is hard to establish guidelines for the administration of phosphate in ICU patients. 20–40 mmol may normally be satisfactory but we have shown that ICU patients may need and can tolerate up to 80 mmol/ day.