Effects of vitamin D and diet magnesium on magnesium metabolism.

Effects of 6-9 days of vitamin D3 (D3), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], or 1,24,25-trihydroxyvitamin D3 [1,24,25(OH)3D3] on Mg metabolism were studied in vitamin D-deficient (-D) rats. Mg absorption expressed as percent intake increased with 1,25(OH)2D3 and 1,24,25(OH)3D3. Urinary Mg (UMg) increased with no change in serum Mg (SMg) or Mg balance.

Bone disease associated with total parenteral nutrition.

An unusual metabolic bone disease which developed in 11 adults receiving total parenteral nutrition (TPN) for more than 3 months was characterised by the insidious onset of bone pain which became very severe and caused considerable disability. Serum levels of calcium, phosphorus, 25-hydroxy-vitamin D, and serum immunoreactive parathyroid hormone were normal. Patchy osteomalacia with impaired mineralisation and decreased bone turnover were seen on histomorphometric analysis of bone biopsy specimens.

Methods for assessing nutritional status of patients with renal failure.

Since wasting and malnutrition are common problems in patients with renal failure, it is important to develop techniques for the longitudinal assessment of nutritional status. This paper reviews available methods for assessing the nutritional status; their possible limitations when applied to uremic patients are discussed. If carefully done, dietary intake can be estimated by recall interviews augmented with dietary diaries.

Calcium and inorganic phosphate transport in rat colon: dissociated response to 1,25-dihydroxyvitamin D3.

In the small intestine, 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] stimulates both calcium (Ca) and inorganic phosphate (Pi) absorption. This is mediated through an increase in mucosal-to-serosal flux (Jms) whereas the serosal-to-mucosal flux (Jsm) remains unchanged. We now report that in rat proximal colon, 1,25(OH)(2)D(3) produces active Ca absorption without affecting Pi transport, and that this induced active Ca absorption is associated with alterations in kinetics of both Jms and Jsm so that both processes demonstrate saturable components.

Kidney stones.

The prevalence of kidney stones has steadily risen during this century; passage of a calculus and a positive family history increase the probability of recurrence. Findings from recent studies on the cause of renal calculi have stressed crystallization and crystal aggregation of stone minerals from supersaturated urine, rather than excessive organic matrix. Absence of normal urine inhibitors of calcium salts is also stressed.

Unique effects of 24,25-dihydroxyvitamin D3 in uremic patients.

The effects of 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), given orally for 7-10 days at doses of 2 and 4 microgram/day, were evaluated in patients with advanced renal failure. There was a significant fall in serum Ca and a rise in alkaline phosphatase; both returned to pretreatment levels 2 weeks after cessation of therapy. There was no change in intestinal absorption of 47Ca.

Interactions between treatment with 1,25(OH)2D3 and glucocorticoids in uremic patients after kidney transplantation.

3 patients undergoing maintenance hemodialysis and receiving 1,25(OH)2D3 for osteomalacic bone disease received cadaveric kidney grafts and concomitant glucocorticoid therapy. The administration of pharmacological doses of glucocorticoids increased the dosage of 1,25(OH)2D3 needed to maintain a normal serum calcium level 7- to 10-fold in 2 patients whose renal grafts failed to function, but there was no decrease in sensitivity to 1,25(OH)2D3 in 1 patient whose renal graft functioned normally. These data suggest that steroids given to a uremic patient may block certain effects normally produced by 1,25(OH)2D3.

Role of growth hormone in experimental phosphorus deprivation in the rat.

The demands of growth are known to exacerbate the effect of phosphorus deprivation (PD). We examined whether changes associated with PD could be prevented in young rats in which growth and growth hormone (GH) were eliminated by hypophysectomy (HPX) and whether PD in normal intact rats (INT) was associated with increased secretion of GH. INT or thyroxine- and ACTH-replaced HPX rats were fed one of the three diets: 0.

Interaction of somatostatin with PTH and AVP: renal effects.

Six conscious intact dogs were studied to evaluate the interactions of somatostatin (SRIF) with exogenous antidiuretic hormone arginine vasopressin (AVP). SRIF administration caused a significant increase in free water clearance compared to a vehicle-treated group: -0.91 (+/- 0.

Applications of the Redy sorbent system to hemodialysis and peritoneal dialysis.

The application of sorbent technology to the treatment of uremia has been limited by the inability to adsorb urea adequately. Conversion of urea to ammonium carbonate and adsorption by zirconium phosphate provides a practical means of removing urea. This combination, together with hydrated zirconium oxide and carbon, removes uremic waste products from dialysate.

Influence of dietary magnesium in experimental phosphate depletion: bone and soft tissue mineral changes.

We studied weanling rats fed 0.06% (group 1) and 0.10% (group II) magnesium (Mg) during phosphate depletion (PD) in order to evaluate the role of Mg in the bone, soft tissue, and serum changes of PD.

Effect of phosphorus depletion on intestinal calcium and phosphorus absorption.

Intestinal calcium (Ca) hyperabsorption is a well-documented feature of experimental phosphorus depletion (PD). To further evaluate the effect of PD on Ca absorption we studied metabolic balance and in vitro everted duodenal sac uptake of Ca and phosphorus (P) in weanling male rats. Animals were assigned to three dietary groups: normal, 0.

Normophosphatemic phosphate depletion in growing rat.

To study the influence of phosphate depletion (PD) on the serum, urinary, bone, and soft tissue phosphorus, we studied growing rats given a high-phosphorus (HP), normal-phosphorus (NP), or low-phosphorus (LP) diet. We obtained the following results. a) With an LP diet, animals did not grow but developed the characteristic biochemical changes of PD.

Interactions between vitamin D deficiency and phosphorus depletion in the rat.

To evaluate the role of vitamin D in the physiologic response to phosphorus depletion (P depleton) and the response to vitamin D administration in P depletion, we studied vitamin D-deficient (-D) rats, fed either a normal or low phosphorus diet and then injected intraperitoneally on alternate days with replacement vitamin D(3), 1.25 mug qod (D(3)); 1.25-dihydroxy-vitamin D(3)[1,25(OH)(2)D(3)] in physiologic, 54 ng qod (LD), and pharmacologic doses, 400 ng qod (HD); or vehicle alone (-D).

Renal osteodystrophy in end-stage renal failure.

Renal osteodystrophy has many skeletal pathologic features, eg, fibroosteoclasia (osteitis fibrosa), osteomalacia, osteopenia, pseudofracture, cyst formation, and osteosclerosis. Many of these are caused by the secondary hyperparathyroidism that usually accompanies renal failure. Derangements in parathyroid hormone secretion, calcium and phosphate metabolism, and renal production of 1,25-dihydroxycholecalciferol (the most active form of vitamin D) are all interrelated and pathogenetic features of renal osteodystrophy.