Therapy of hypercalcemia of malignancy

An appreciation of the pathogenesis of the hypercalcemia of malignancy is essential to its management. At the outset, since most patients with symptomatic hypercalcemia of malignancy are dehydrated, infusion of 2 to 3 liters of saline per day will at least partially reduce serum calcium levels. Induction of calciuresis by infusing larger volumes of saline simultaneously with parenteral administration of furosemide may reduce the serum calcium concentration to normal in the short term. Of major importance in long-term therapy, however, are drugs that inhibit bone resorption, a major cause of hypercalcemia. These include calcitonin, plicamycin, glucocorticoids, prostaglandin synthetase inhibitors, and the diphosphonates. These agents may provide long-term control of hypercalcemia in many patients. Reduction of intestinal calcium absorption by dietary means or by glucocorticoid therapy is often effective in the rare subset of patients with increased serum levels of 1,25-dihydroxyvitamin D. Oral and intravenous phosphorus therapy may be effective via unknown mechanisms in some patients. The diphosphonates, in particular, should greatly facilitate management of both acute and chronic hypercalcemia of malignancy. Daily intravenous infusion of etidronate disodium (etidronate) with saline over a period of three to six days, for example, appears to be a safe and effective means of restoring serum calcium concentrations to the normal range. Study results have shown that more than 90 percent of patients have a response to etidronate. Oral administration of the drug has been demonstrated to maintain normal serum calcium concentrations.

Hypophosphatemic rickets/osteomalacia in linear sebaceous nevus syndrome: a variant of tumor-induced osteomalacia

A severe form of vitamin D-resistant rickets is associated with the linear sebaceous nevus syndrome. We investigated the pathophysiology underlying defective bone mineralization in two individuals and examined the effects of 1,25-dihydroxyvitamin D (1,25(OH)2D, calcitriol) therapy on the clinical and biochemical abnormalities. Both patients had fasting hypophosphatemia, markedly diminished TmP/GFR, and elevated alkaline phosphase activity in the presence of normocalcemia. Before treatment with calcitriol, serum 1,25(OH)2D concentrations were reduced but serum 25-hydroxyvitamin D (25(OH)D) concentrations were normal. Administration of calcitriol increased serum 1,25(OH)2D concentrations and led to an increase in TmP/GFR and serum phosphorus levels and to a decrease in alkaline phosphatase activity. However, the renal tubular maximum for reabsorption of inorganic phosphate, normalized according to glomerular filtration rate, and serum phosphorus levels remained abnormally low even in the patient who also received phosphate supplementation. Bone histomorphologic studies in the adult patient showed extreme osteomalacia, which partially improved with calcitriol. These data demonstrate that the putative skin lesion-derived factor results in both a renal tubular defect in phosphate reabsorption and in 1,25-(OH)2 D deficiency. The vitamin D-resistant rickets of linear sebaceous nevus syndrome is a variant of tumor-induced osteomalacia.

Kidney function in rats with corticomedullary nephrocalcinosis: effects of alterations in dietary calcium and magnesium

Single-nephron and whole-kidney function were studied in female rats with corticomedullary nephrocalcinosis, and in animals where the lesion had been prevented either by a dietary magnesium supplement or by using a diet with a calcium:phosphorus ratio in excess of 1. At the single-nephron level, rats with nephrocalcinosis had prolonged tubular fluid transit times. Proximal transit time was 19.42 +/- 1.98 (mean +/- S.E. of mean) vs. 11.58 +/- 0.19 s for controls; distal transit time was 62.64 +/- 9.16 vs. 31.50 +/- 1.03 s for controls. Although single-nephron function is altered in nephrocalcinosis, data obtained from rats in metabolism cages indicate that whole-kidney function is largely unaffected by the lesion.

A single case of hypophosphatemic rickets with hypercalciuria

A single case of hypophosphatemic rickets with hypercalciuria and an elevated level of serum 1,25 dihydroxyvitamin D is reported. The characteristic features (genu valgum, rickets, short stature, increased renal phosphate excretion, decreased serum phosphorus level, elevated serum alkaline phosphatase level, and normal serum calcium level) were comparable to those in hypophosphatemic vitamin D resistant rickets. Massive doses of 1 alpha-hydroxyvitamin D were not effective for the rickets and the biochemical defect in this patient. Long-term phosphate supplementation on its own resulted in the reversal of all clinical and biochemical abnormalities except for the decreased ratio between the maximum tubular reabsorption rate for phosphorus and the glomerular filtration rate. In this patient, the concentration of serum 1,25 dihydroxyvitamin D seemed to be controlled by the concentration of serum phosphorus rather than by the serum parathyroid hormone level. It is noted that this is the first case of a single hypophosphatemic rickets with hypercalciuria.

Diet calcium carbonate, phosphorus and acidifying and alkalizing salts as factors influencing silica urolithiasis in rats fed tetraethylorthosilicate

Three experiments were conducted to determine the effects of excess dietary calcium carbonate, phosphorus and urine acidifying and alkalizing salts on silica urolith formation in a model using rats fed dextrose-based diets containing 2% tetraethylorthosilicate (TES). Diets containing 2% TES lowered weight gains to 91-95% of gains made by rats fed non-TES diets. Urine silica concentrations of rats fed TES were generally in the range of 50-60 mg/dl. In experiment 1, rats fed TES with no additional dietary calcium carbonate had a silica urolith incidence of 35%. With additions of 1 and 2% calcium carbonate to the basal-TES diet, respective urolith incidences were 45 and 60% (r = 0.99, P less than 0.02). In experiment 2, monobasic sodium phosphate (MP) providing 0.2% additional phosphorus resulted in a mean urine pH of 6.42 and no uroliths. Dibasic sodium phosphate (DP) without and with 0.5% sodium bicarbonate (SB) resulted in respective urine pH values of 6.78 and 7.14 and urolith incidences of 15 and 20% (MP less than DP and DP + SB, P less than 0.05). However, the uroliths were small averaging less than 1 mg. In experiment 3, substitution of autoclaved egg albumin for casein, the protein source in experiments 1 and 2, resulted in urine pH of 7.45 and a silica urolith incidence of 46%. An equal-molar mixture of MP and DP providing an added 0.2% phosphorus resulted in a urine pH of 7.07 and reduced the urolith incidence to 4%, and 0.75% of dietary ammonium chloride either with or without the added 0.2% phosphorus gave urine acidification and complete protection from uroliths.(ABSTRACT TRUNCATED AT 250 WORDS)

Controversies in neonatal nutrition

The assessment of growth parameters remains one of the most practical and valuable tools to estimate nutritional status in neonates. Growth assessment in full-term infants is performed by using charts developed by the National Center for Health and Statistics. The assessment of post-natal growth in premature infants is controversial and can be performed by using either intrauterine or extrauterine standards. The selection of appropriate growth charts should be based on clinical, demographic, ethnic, and socioeconomic similarities of the population used for reference. Daily energy intakes ranging from 100 to 120 kcal/kg/day have been recommended for full-term infants, while higher intakes ranging from 114 to 181 kcal/kg/day have been recommended for premature neonates. Full-term infants should be nursed or nipple fed on demand; however, premature infants should ideally be tube fed by intermittent gastric feeding (gavage). Continuous gastric and transpyloric feedings are indicated in selected infants. Human milk is a preferred food for full-term infants during the first six months of life; however, this precept does not suggest that all infants who are exclusively breast-fed will grow adequately. Preterm human milk is also a preferred food for the low birthweight infant, provided nutritional supplements are used. It is unclear whether the supplementation of vitamin D, iron, and fluoride in full-term breast-fed infants should be started at birth, at the time of initiation of solid foods, or at the age of six months. The routine supplementation of multivitamins, folic acid, and vitamin E to all low birthweight infants is controversial. Most investigators suggest vitamin supplementation be given until the intake of formula or breast milk is sufficient to meet daily requirements. Vitamin E appears to exert a protective effect in premature infants against the development of severe retinopathy. The supplementation of vitamin E should be dependent upon the serum vitamin E concentration. It is controversial whether iron supplementation for premature infants should be initiated soon after birth or at two months of age, or whether higher doses of iron should be given to very low birthweight infants. If iron supplementation is started at birth, vitamin E status should be closely monitored. Although the optimal intakes of calcium and phosphorus in infant feedings have not been firmly established, the levels of calcium and phosphorus in human milk appear to be inadequate for the growing low birthweight infant.(ABSTRACT TRUNCATED AT 400 WORDS)

[Biological and bone histomorphometric studies in hypophosphatemic vitamin-resistant rickets treated with 1,25-(OH)2D and phosphorus]

Five children aged 6 to 15 years were studied. They presented all the biological signs of hypophosphatemic vitamin resistant rickets: normal calcemia, hypophosphatemia, decrease in phosphorus Tm and normal PTH plasma level. Two children had never been given vitamin D treatment previously. The 1.25 (OH)2D has been given in 4 doses a day, to a total of 1 microgram/day, for one year. Phosphate was administered for the same time, doses varying from 40 to 150 mg/kg/day. Bone biopsies were performed at the onset and the end of treatment. Normal growth concerning bone age was observed in 3 cases. In the two others, growth remained disturbed. Radiological recovery was observed in all cases. Treatment induced and increase in serum phosphate. Tm PO4/FG remained lower than normal and even decreased during treatment. After one year of treatment, the osteoid volumes and surfaces decreased in all cases but did not always return to normal. The thickness index of osteoid and the speed of calcification were improved in 4 cases and worsened in the 5th. In two previously untreated patients an increase in plasma PTH and in the osteoclastic surface of resorption were observed on the bone biopsy during treatment.

Healing of bone disease in X-linked hypophosphatemic rickets/osteomalacia. Induction and maintenance with phosphorus and calcitriol

Although conventional therapy (pharmacologic doses of vitamin D and phosphorus supplementation) is usually successful in healing the rachitic bone lesion in patients with X-linked hypophosphatemic rickets, it does not heal the coexistent osteomalacia. Because serum 1,25-dihydroxyvitamin D levels are inappropriately low in these patients and high calcitriol concentrations may be required to heal the osteomalacia, we chose to treat five affected subjects with high doses of calcitriol (68.2 +/- 10.0 ng/kg total body weight/d) and supplemental phosphorus (1-2 g/d) performing metabolic studies and bone biopsies before and after 5-8 mo of this therapy in each individual. Of these five patients, three (aged 13, 13, and 19 yr) were receiving conventional treatment at the inception of the study and therefore showed base-line serum phosphorus concentrations within the normal range. The remaining two untreated patients (aged 2 and 37 yr) displayed characteristic hypophosphatemia before calcitriol therapy. All five patients demonstrated serum calcitriol levels in the low normal range (22.5 +/- 3.2 pg/ml), impaired renal phosphorus conservation (tubular maximum for the reabsorption of phosphate per deciliter of glomerular filtrate, 2.13 +/- 0.20 mg/dl), and osteomalacia on bone biopsy (relative osteoid volume, 14.4 +/- 1.7%; mean osteoid seam width, 27.7 +/- 3.7 micron; mineral apposition rate, 0.46 +/- 0.12 micron/d). On high doses of calcitriol, serum 1,25-dihydroxyvitamin D levels rose into the supraphysiologic range (74.1 +/- 3.8 pg/ml) with an associated increment in the serum phosphorus concentration (2.82 +/- 0.19 to 3.78 +/- 0.32 mg/dl) and improvement of the renal tubular maximum for phosphate reabsorption (3.17 +/- 0.22 mg/dl). The serum calcium rose in each patient while the immunoactive parathyroid hormone concentration measured by three different assays remained within the normal range. Most importantly, repeat bone biopsies showed that high doses of calcitriol and phosphorus supplements had reversed the mineralization defect in all patients (mineral apposition rate, 0.88 +/- 0.04 micron/d) and consequently reduced parameters of bone osteoid content to normal (relative osteoid volume, 4.1 +/- 0.7%; mean osteoid seam width, 11.0 +/- 1.0 micron). Complications (hypercalcemia and hypercalciuria) ensued in four of these five patients within 1-17 mo of documented bone healing, necessitating reduction of calcitriol doses to a mean of 1.6 +/- 0.2 micrograms/d (28 +/- 4 ng/kg ideal body weight per day). At follow-up bone biopsy, these four subjects continued to manifest normal bone mineralization dynamics (mineral apposition rate, 0.88 +/-0.10 micrometer/d) on reduced doses of 1.25-dihydroxyvitamin D with phosphorus supplements (2 g/d) for a mean of 21.3 +/- 1.3 mo after bone healing was first documented. Static histomorphometric parameters also remained normal (relative osteoid volume, 1.5 +/- 0.4%; mean osteoid seam width, 13.5 +/- 0.8 micrometer). These data indicate that administration of supraphysiologic amounts of calcitriol, in conjunction with oral phosphorus, results in complete healing of vitamin D resistant osteomalacia in patients with X-linked hypophosphatemic rickets. Although complications predictably require calcitriol dose reductions once healing is achieved, continued bone healing can be maintained for up to 1 yr with lower doses of 1,25-dihydroxyvitamin D and continued phosphorus supplementation.

Rickets of prematurity: calcium and phosphorus supplementation

Seventy-four infants weighing less than 1500 gm at birth were fed enterally from birth until day 47. Group A (18 infants) were given SMA Gold Cap: group B (18 infants), supplementary calcium to 21 mmol/L (84 mg/dl); group C (16 infants), further calcium supplementation to 31.2 mmol/L (125 mg/dl); and group D (22 infants), milk with calcium content 31.2 mmol/L (125 mg/dl) and phosphorus supplementation to 15.7 mmol/L (49 mg/dl). The addition of calcium reduced the radiologic evidence of rickets, and combined calcium and phosphorus supplementation maintained plasma alkaline phosphatase activity within the normal range for 6 weeks.

Renal magnesium and phosphate wastage in a patient with hypercalciuria and nephrocalcinosis: effect of oral phosphorus and magnesium supplements

We report a 29-year-old man with a mild decrease in glomerular filtration, nephrocalcinosis, hypercalciuria and a renal magnesium leak. He had other features of 'congenital magnesium-losing kidney', such as arthritis and hyperuricemia, short stature and recurrent urinary tract infections, but had no radiological chondrocalcinosis. In addition, pallidal calcification was found. The patient also had a renal phosphate leak. Phosphorus supplements resulted in a decrease in urinary calcium excretion, indicating that hypercalciuria was at least partially a consequence of phosphorus depletion. Plasma and urine magnesium were not affected by phosphorus supplements. Addition of magnesium supplements resulted in a transient and modest decrease in urinary calcium excretion, with no modification in plasma magnesium.

Hypercalciuric rickets: metabolic studies and pathophysiological considerations

Extensive metabolic studies were performed in a 14-year-old boy suffering from the rare clinical entity known as childhood idiopathic hypercalciuria associated with dwarfism, renal tubular abnormalities and bone lesions. The salient features were: hyperphosphaturia with hypophosphatemia, hypercalciuria with normocalcemia, elevated serum 1,25-dihydroxycholecalciferol[1,25(OH)2D3] levels, marked intestinal hyperabsorption of calcium and phosphorus, with low serum parathyroid hormone (PTH) and urinary adenosine 3':5'-cyclic monophosphate (c-AMP). Bone biopsy confirmed the clinical and radiological diagnosis of rickets. It appears that the following pathophysiological sequence is operating: primary renal phosphate leak with hypophosphatemia, increased 1,25(OH)2D3 synthesis, enhanced intestinal calcium absorption which in turn inhibits release of PTH and c-AMP. Hypercalciuria is seen to be secondary to both avid intestinal calcium absorption and depressed PTH activity, and rickets the result of phosphate depletion. Treatment with oral phosphorus only resulted in an acceleration of growth rate, cure of rickets, and return of urinary calcium excretion to normal values.

Hypercalcaemia in extremely low birthweight infants

We report 10 cases of hypercalcaemia associated with hypophosphataemia in the first two weeks of life in extremely low birthweight infants (birthweight less than 1000 g). At the time of diagnosis, the infants were fed mainly with expressed breast milk but they had also received intravenous nutrition. After treatment with additional phosphate plasma calcium concentrations returned to normal. There was a high incidence of rickets of prematurity in these infants.

Bone histomorphometry in vitamin D-deficient rats infused with calcium and phosphorus

Defective mineralization of bone and cartilage is the classical histological finding in vitamin D deficiency. Whether this represents a direct effect on mineral deposition or is a consequence of the decreased calcium and phosphorus levels that result from impaired intestinal absorption is not clear. A method has been developed in which vitamin D-deficient rats have plasma calcium and phosphorus levels maintained in the normal range by continuous infusion. Histomorphometric analysis of undecalcified tibiae from these animals was compared with that of rats given vitamin D. Epiphyseal growth plate thickness, trabecular osteoid volume, and mean osteoid seam width were not increased. Moreover, the administration of two time-spaced courses of tetracycline revealed that the mineralization rate and the time interval between apposition and subsequent mineralization of osteoid (mineralization lag time) were identical to those in rats treated with vitamin D. Trabecular bone volume was increased (osteosclerosis) in the vitamin D-deficient rats. In vitamin D-deficient controls without infusions, the osteosclerosis was mostly osteoid, whereas the excess bone was well mineralized in the vitamin D-deficient rats infused with calcium and phosphorus. Osteosclerosis in vitamin D-deficient animals may result from both decreased bone resorption and increased osteoid apposition. This study provides firm evidence that vitamin D is not essential for mineralization in young growing rats. Decreased availability of calcium and phosphorus thus may be the sole basis of the mineralization defect seen in vitamin D deficiency.

[Incidence of lithiasic recurrence after a diuretic therapy, alone or combined with treatment by a thiazide diuretic or phosphorus]

The preventive affects on recurrent renal calcium stones of water diuresis alone or combined with drugs aimed at lowering urinary calcium were evaluated prospectively in 51 patients with calcium nephrolithiasis. Following clinical and metabolic examination, the patients were allocated at random to 3 treatment groups: water diuresis alone (group I, n = 19) or associated with hydrochlorothiazide 50 mg/day (group II, n = 19) or with a neutral phosphate preparation 1500 mg/day (group III, n = 13). Results were assessed on the number of recurrences; 24-h urinary calcium was measured at regular intervals. The mean follow-up (2 years; range 1-4 years) was the same in all 3 groups. A significant fall in recurrence rate as compared with pre-treatment values was observed in groups I and II. The recurrence rate was the same in both groups during treatment. However, less patients had recurrences in group I (1/19) than in group II (5/19). No significant fall in recurrence rate was observed in group III, owing to some patients in this group having frequent recurrences. The recurrence rate was unrelated to clinical findings and biochemical values ( oxaluria , calciuria) measured before treatment and to the urinary Ca/Cr ratio calculated during treatment. This study confirms that water diuresis is effective in preventing recurrent renal calcium stones and that diuretics of the thiazide group reduce the number of patients with recurrences.

Skeletal calcium homeostasis and countermeasures to prevent disuse osteoporosis

Maintenance of a skeleton capable of resisting the stresses of everyday life is dependent on the mechanical forces applied to the skeleton during normal activity in a 1-G environment. When the effects of 1-G on the longitudinal skeleton are removed, as with space travel or inactivity, bone and bone mineral are lost because bone resorption is greater than bone formation. Ninety healthy young men were studied during 5-36 weeks of continuous bed rest. During inactivity, urinary calcium increases rapidly and by the sixth week of bed rest, output has risen by 100 mg/day, plateaus for several weeks, and then decreases but remains above ambulatory baseline thereafter. This occurred even though they received vitamin D supplements throughout the study. Calcium balance becomes negative after 2 weeks and by the end of the first month, 200 mg/day is lost. The loss continues at this rate for at least 36 weeks. Calcaneal mineral loses 5% of its mass each month. Attempts to prevent disuse osteoporosis with both mechanical and biochemical means, including exercise, skeletal compression, increased hydrostatic pressure to the lower body, supplemental calcium and/or phosphorus, calcitonin, or etidronate were not successful.

Premature cranial synostosis in X-linked hypophosphatemic rickets: possible precipitation by 1-alpha-OH-cholecalciferol intoxication

A child suffering from X-linked hypophosphatemic rickets developed vitamin D intoxication under treatment with 1-alpha-OH-cholecalciferol (1(OH)D3) and phosphorus. Beside the usual findings in this condition he showed precocious synostosis of the skull with signs of raised intracranial pressure. In view of earlier reports of coincidence of craniostenosis and X-linked hypophosphatemic rickets, we conclude that the possibility exists that intoxication with 1(OH)D3 has been the precipitating factor. In addition we found hypersensitivity to 1(OH)D3 2 months after cessation of treatment, and normal levels of calcitriol (1,25(OH)2D3) at the same time.

Rickets in a preterm infant during intravenous alimentation

A preterm baby given intravenous feeding developed severe rickets. Laboratory investigation revealed hypophosphatemia as the main cause of this picture. Recovery was achieved by giving extra phosphorus supplementation. This case demonstrates that conventional infusates do not meet the phosphorus requirement of rapidly growing infants.

[Diet and chronic renal failure]

In the last 10 years the diet severely restricted in proteins advocated by GIORDANO and GIOVANNETTI in the treatment of chronic renal failure has fallen out of use because in the long term it induced cachectic states in most patients. In recent months, however, experimental studies have pointed to the negative effect protein intake may have on renal function. Glomerular hyperfiltration induced by protein intake may lead to proteinuria and glomerulosclerosis, which in turn aggravates impaired renal function and glomerular hyperfiltration. Some clinical studies appear to confirm the beneficial effect on the progression of renal failure when diets containing 15-30 g protein per day are instituted. This new approach may be of considerable practical importance but at present most of these studies need confirmation and generalized uncontrolled administration of diets severely restricted in proteins is not yet justified.

A detailed evaluation of oral phosphate therapy in selected patients with primary hyperparathyroidism

Recent studies have emphasized the pathophysiological importance of circulating 1,25-dihydroxyvitamin D ((1,25-(OH)2D] in the pathogenesis of hypercalciuria and renal stone formation in primary hyperparathyroidism. Reasoning that phosphate administration might be capable of reducing the plasma concentration of 1,25-(OH)2D in patients with a prominent 1,25-(OH)2D-mediated absorptive component to their disease, 10 carefully selected patients were treated with oral phosphate (1500 mg elemental phosphorus daily) for 1 yr. Phosphate treatment significantly reduced circulating 1,25-(OH)2D levels (84 to 56 pg/ml), the calciuric response to an oral calcium tolerance test (0.30 to 0.21 delta mg calcium/dl GF), and calcium excretion on an unrestricted calcium diet (438-269 mg/day), in essence reversing the absorptive pattern of abnormalities observed before treatment. This response, however, was accompanied by an increase in biochemical hyperparathyroidism, as assessed by circulating immunoreactive PTH and nephrogenous cAMP excretion. In patients with biochemical evidence of an increase in bone resorption before therapy, histomorphometric, radiographic, and biochemical data revealed a trend toward a reduction in bone turnover during phosphorus therapy, with an apparent maintenance of coupled bone resorption and bone formation. This trend, however, was of marginal statistical significance in the patient group as a whole. It is concluded 1) that phosphate therapy represents a viable medical alternative in selected patients with primary hyperparathyroidism, 2) that the net response in treated patients is multifaceted and complex, and 3) that the efficacy of phosphate therapy will ultimately depend upon its long term effects on skeletal homeostasis.

Therapy of malignancy-associated hypercalcemia: 1983

Hypercalcemia is common among patients with cancer and may be due to secretion by tumors of a humoral, calcemic, bone-resorbing factor or, alternatively, to skeletal metastases. In each case, hypercalcemia ultimately results from osteoclastic bone resorption. Therapy should be aimed at (1) reducing or eliminating tumor burden, (2) increasing renal calcium clearance, and (3) inhibiting osteoclastic bone resorption. Hydration with saline infusion and augmentation of calciuresis with furosemide should be the initial modes of therapy in most patients. Oral phosphorus should be used in hypophosphatemic patients. Glucocorticoids, calcitonin, and prostaglandin synthetase inhibitors may be effective in reducing bone resorption in selected patients. Mithramycin reliably induces a fall in serum calcium but long-term use is usually complicated by toxicity. A new class of drugs that inhibit osteoclastic bone resorption, the diphosphonates, is being employed in clinical trials in patients with malignancy-associated hypercalcemia. Results have been particularly promising with dichloromethylene diphosphonate.

Humoral hypercalcemia of malignancy: a syndrome in search of a hormone

A women with hypercalcemia and a hypernephroma confined to the left kidney underwent nephrectomy and subsequent resolution of hypercalcemia. Serum parathyroid hormone was undetectable in peripheral blood as well as in the left renal vein at surgery. Parathyroid hormone was also undetectable in the tumor extract using three different antisera to parathyroid hormone. Measurement of plasma prostaglandin E and 13, 14-dihydro-15-keto-prostaglandin E2 revealed levels within the normal range. The serum 1,25-dihydroxyvitamin D concentration was below normal and nephrogenous cyclic adenosine monophosphate was markedly elevated. The humoral agent responsible for hypercalcemia in this patient was not identified. This case emphasizes the need to search for new hypercalcemic factors in patients with hypercalcemia of malignancy.

Vitamin D metabolism in hypophosphatemic rickets

Vitamin D metabolites were measured in 21 patients with hypophosphatemic osteomalacia of juvenile onset. In eight patients who had not received any antirachitic treatment, serum 25-hydroxyvitamin D(25-OH-D) and 1,25-dihydroxyvitamin D (1,25-[OH]2D) values were normal, whereas serum 24,25-dihydroxyvitamin D (24,25-[OH]2D) values were lower than in normal subjects. In 13 patients who were receiving ergocalciferol and oral elemental phosphorus, serum 25-OH-D and 24,25-(OH)2D concentrations were elevated and serum 1,25-(OH)2D values were low. The findings in untreated patients supported the hypothesis that vitamin D metabolism is abnormal in hypophosphatemic rickets/osteomalacia. The reduction of serum 1,25-(OH)2D levels with ergocalciferol and phosphate therapy gives further support to a therapeutic role for 1,25-(OH)2D in this disorder.

Treatment of refractory hypophosphatemia

Profound hypophosphatemia developed in a patient with chronic alcoholism. Multiple causative factors were identified and were thought to account for the initial failure of phosphorus repletion. High-dose intravenous phosphorus was effective in restoring serum phosphorus to normal with no observable adverse effects. Because of the high degree of correlation between hypophosphatemia and hypomagnesemia, we recommended that serum magnesium be determined in all hypophosphatemic patients.

[Mechanism of the antiarrhythmic effect of inorganic phosphates in digitalis poisoning]

THe synergistic effects between calcium and the therapeutic and toxic actions of the cardiac glycosides have suggested that a way of treating digitalis intoxication could be through a decrease in free plasma calcium. In 1966, Burckhardt and La-Due published a study based on the inverse relationship that exists between plasma phosphates and calcium. It was shown then that potassium phosphate had a pronounced antiarrhythmic effect on digitalis induced arrhythmias. The use of potassium phosphate for this study prevented the analysis of the role of the phosphates in these effects, since the actions of potassium in digitalis toxicity precluded any conclusion. The purpose of the present paper is to study the effect of phosphates on digitalis intoxication and its possible mechanism of action. The results obtained demonstrated: 1) Phosphates have a marked antiarrhythmic effect in digitalis induced arrhythmias. 2) This effect is due to a decrease in free plasma calcium. 3) The lowering of this calcium pool occurs in the blood and is not mediated by hormonal or renal mechanisms. 4) The ions that disappear from the free calcium pool do not precipitate. 5) The use of phosphates could be useful in the treatment of some clinical cases of advanced digitalis intoxication.

Etiologic factors in rickets of very low-birth-weight infants

The incidence of rickets was found to be 32% (39/125) in a retrospective review of consecutive survivors of very low birth weight in whom serial radiographic and biochemical data were obtained. A higher proportion of these infants were black, had a greater initial weight loss, and had a longer hospitalization; there was a prevalence of births in the spring. Soy formula, supplemented with calcium and vitamin D but not phosphorus, was used predominantly in both groups; cumulative calcium, phosphorus, vitamin D, and caloric intakes were the same. We believe that the etiology of rickets in VLBW infants is multifactorial; however, nutritional deficiency is of central importance. Soy isolate formula, as well as human milk and many other commercially available formulas, do not provide sufficient calcium and phosphorus to keep pace with rates of intrauterine accretion. Supplementation with calcium, phosphorus, and vitamin D, beginning as soon as possible after birth, is indicated.

Plasma vitamin D metabolites in a patient with sporadic hypophosphataemic osteomalacia (adult-onset type)

Sporadic hypophosphataemic osteomalacia (adult-onset type) was demonstrated in a 40-year-old man on the basis of severe osteomalacia, hypophosphataemia, hyperphosphaturia and glycinuria. Plasma immunoreactive parathyroid hormone (iPTH) concentration was 9.3 ng prot./ml (normal range: 4-8 ng prot./ml). Plasma 25-hydroxy-vitamin D and 24,25-dihydroxy-vitamin D concentrations were 11 and 2.4 ng/ml respectively. Basal 1 alpha,25-dihydroxy-vitamin D concentrations were slightly elevated (116 and 96 pg/ml) and increased to 240 pg/ml after 3 days on a low-phosphorus diet. The patient was put on oral treatment with 25-hydroxycholecalciferol (100 microgram per day) and phosphorus (1500 mg per day). On the 4th month on treatment, a clinical improvement was apparent. Plasma 25(OH)D was 44 ng/ml, plasma 1,25(OH)2D was 256 pg/ml. However, plasma phosphorus remained low (0.77 mmol/l). On the 9th month of treatment a radiological improvement was evident despite a persistent hypophosphataemia (0.68 mmol/l). These facts suggest in our patient the existence of a vitamin D-independent renal phosphorus leak.

Diabetic ketoacidosis. Reassessment of therapeutic "truths"

The diagnosis of diabetic ketoacidosis remains, as always, a bedside clinical exercise. Rapid consideration and exclusion of other conditions associated with altered consciousness that may occur in diabetics, such as lactic acidosis, hyperosmolar states, hypoglycemia, alcohol-related ketosis, and infections, should be routine. Although recent reassessment of therapy has meant more rational and specific action, close attention to the physical and laboratory responses to treatment is equally essential for a successful outcome.

[Comparison of treatments in senile osteoporosis: follow up for 12 months (author's transl)]

We randomly divided senile osteoporotic patients into 8 groups. Eleven patients of A-Group were treated daily with 900 mg of calcium and 50 mg of sodium fluoride and 50,000 units of vitamin D twice weekly. Fourteen patients of B-Group were treated daily with 900 mg of calcium and 50 mg of sodium fluoride. Twelve patients of C-Group were treated daily with 50 mg of sodium fluoride. Ten patients of D-Group were treated daily with 900 mg of calcium, 50 mg of sodium fluoride and 2 mg of estriol. Ten patients of E-Group were treated daily with 2 mg of estriol. Ten patients of F-Group were treated daily with 900 mg of calcium. Ten patients of G-Group were treated daily with 900 mg of calcium and 2 mg of estriol. The treatments were given for 12 months. Ten patients without treatment served as the non-treated control group. In each group, mineral contents were measured with Norland Bone Mineral Analyzer at the level of the distal third of the left radius and ulna before and after treatment. Mineral contents of ulnar bone in A-Group, of radial and ulnar bones in E-Group, F-Group, and G-Group increased with statistical significance after 12 months of the therapy. Mineral contents of radial and ulnar bones in C-Group and Nontreated Group decreased with statistical significance after 12 months. In laboratory examination, we observed no severe side-effect in our patients. But it was very interesting that the values of serum alkaline phosphatase in F-Group and G-Group decreased with statistical significance after 12 months of the therapies.

[Hypophosphatemic vitamin D resistant osteomalacia with parathyroid adenoma (author's transl)]

The authors report a new case of parathyroid adenoma associated with hypophosphatemic vitamin D resistant osteomalacia. These troubles were simultaneously found. Major and isolated phosphate tubular loss was improved neither by parathyroidectomy nor vitamin D or 25 OHD therapy. On the contrary 25 OHD associated with oral phosphate intake was clinically, radiologically and histologically efficient. The actual pathogenic concepts about this affection are reviewed.

Rickets with alopecia: an inborn error of vitamin D metabolism

Rickets with alopecia, an inborn error of vitamin D metabolism, is described in two sisters. The rachitic disorder began during the first year of life and was refractory to 50,000 IU of vitamin D2/day. Surprisingly, both children had marked elevations in serum concentrations of 1,25-(OH)2D. Although the molecular basis for this disorder is not evident to date, intestinal end-organ unresponsiveness to exceedingly high levels of 1,25-(OH)2D was present, in addition to hyporesponsiveness of bone to these high levels of the hormone, since normocalcemia was maintained despite elevated serum levels of PTH. Therapy with oral 1,25-(OH)2D3 failed to reverse the disorder, but oral phosphorus supplements resulted in significant radiographic and clinical improvement.

Evidence for the promotion of bone mineralization by 1alpha,25-dihydroxycholecalciferol in the rat unrelated to the correction of deficiencies in serum calcium and phosphorus

Concurrent administration of 1alpha,25-dihydroxycholecalciferol [1alpha,25-(OH)2-CC] to intact and thyroparathyroidectomized rats treated with ethane-1-hydroxy-1,1-diphosphonate (EHDP) prevented or reversed the EHDP-induced inhibition of bone mineralization as measured by changes in epiphyseal plate width and ash content of bone. An analog, 1alpha-droxycholecalciferol, was also effective. Recovery of bone after EHDP treatment was also significantly improved by administration of 1alpha,25-(OH)2-CC as evidenced by enhanced uptake of 45Ca by epiphyseal plates and decreased plate widths. Cholecalciferol (CC), ergocalciferol, dihydrotachysterol2, 5,6-trans-CC, 25-OH-CC, 5,6-Trans-25-OH-CC, and 1alpha24R,25-(OH)3-CC also blocked EHDP-induced epiphyseal plate widening, but required high, pharmacological dose levels. 24R,25- (OH)2-CC was inactive at doses up to 10 microgram/day. Since EHDP-treated rats are not deficient in calcium or phosphate, these data suggest that 1alpha,25-dihydroxycholecalciferol promoted bone mineralization independently of effects upon the intestinal absorption of calcium and phosphate.

Treatment of severe hypophosphatemia

Aspects of phosphate biochemistry pertinent to therapy, the distribution of phosphorus in body compartments, therapeutic phosphorus preparations, prevention of hypophosphatemia, therapeutic guidelines, and side-effects of phosphorus therapy are reviewed. Severe hypophosphatemia (less than 0.32 mmol/litre or less than 1 mg/dl) can occur with normal or depleted body stores. Because a large amount of phosphorus may shift rapidly between the extracellular and intracellular or bone compartments, the size of a possible total body deficit cannot be estimated from the serum phosphorus level. Similar shifts may occur unpredictably during repair of hypophosphatemia. Therefore, correction of hypophosphatemia in any patient must be empiric and the response of serum levels to therapy should be followed closely. We discuss a method likely to correct hypophosphatemia while minimizing side-effects.

Rickets in growing pigs and response to treatment

The clinical, radiological and pathological findings in a natural outbreak of rickets affecting 82 pigs are described. An interesting feature was the presence of gross articular abnormalities including resorption of subchondral bone with folding and ulceration of the articular cartilage. The diet was deficient in calcium and vitamin D. A diagnosis of rickets complicated by nutritional secondary hyperparathyroidism was made. The results of treatment and the economics of the outbreak are discussed.