Jack W. Coburn

Cinacalcet HCl, an Oral Calcimimetic Agent for the Treatment of Secondary Hyperparathyroidism in Hemodialysis and Peritoneal Dialysis: A Randomized, Double-Blind, Multicenter Study

Management of secondary hyperparathyroidism is challenging with traditional therapy. The calcimimetic cinacalcet HCl acts on the calcium-sensing receptor to increase its sensitivity to calcium, thereby reducing parathyroid hormone (PTH) secretion. This phase 3, multicenter, randomized, placebo-controlled, double-blind study evaluated the efficacy and safety of cinacalcet in hemodialysis (HD) and peritoneal dialysis (PD) patients with PTH > or =300 pg/ml despite traditional therapy. A total of 395 patients received once-daily oral cinacalcet (260 HD, 34 PD) or placebo (89 HD, 12 PD) titrated from 30 to 180 mg to achieve a target intact PTH (iPTH) level of < or =250 pg/ml. During a 10-wk efficacy assessment phase, cinacalcet was more effective than control for PTH reduction outcomes, including proportion of patients with mean iPTH levels < or =300 pg/ml (46 versus 9%), proportion of patients with > or =30% reduction in iPTH from baseline (65 versus 13%), and proportion of patients with > or =20, > or =40, or > or =50% reduction from baseline. Cinacalcet had comparable efficacy in HD and PD patients; 50% of PD patients achieved a mean iPTH < or =300 pg/ml. Cinacalcet also significantly reduced serum calcium, phosphorus, and Ca x P levels compared with control treatment. The most common side effects, nausea and vomiting, were usually mild to moderate in severity and transient. Once-daily oral cinacalcet was effective in rapidly and safely reducing PTH, Ca x P, calcium, and phosphorus levels in patients who received HD or PD. Cinacalcet offers a new therapeutic option for controlling secondary hyperparathyroidism in patients with chronic kidney disease on dialysis.

Hypercalcemia in an Anephric Patient with Sarcoidosis: Evidence for Extrarenal Generation of 1,25-Dihydroxyvitamin D

HYPERCALCEMIA can occur in up to 10 per cent of patients with sarcoidosis.1 , 2 During the active phase of the disease, increased absorption of calcium from the intestine leads to hypercalciuria an...

Intravenous Calcitriol in the Treatment of Refractory Osteitis Fibrosa of Chronic Renal Failure

Osteitis fibrosa, a frequent complication of chronic renal failure, is characterized by increased rates of bone formation and bone resorption due to increased secretion of parathyroid hormone (PTH). Effective treatment with oral calcitriol is often impossible in patients with osteitis fibrosa, because low doses may cause hypercalcemia. Because short-term infusions of intravenous calcitriol are capable of suppressing the secretion of parathyroid hormone in patients with uremia without causing hypercalcemia, we evaluated the effectiveness of long-term intermittent calcitriol infusions (1.0 to 2.5 micrograms three times weekly, during dialysis) in treating severe osteitis fibrosa in 12 consecutive patients on hemodialysis whose disease was refractory to conventional therapy. After a mean (+/- SE) treatment period of 11.5 +/- 1.4 months, the mean bone-formation rate declined from 1642 +/- 277 to 676 +/- 106 microns 2 per square millimeter per day (P less than 0.01) in the 11 patients who successfully completed the study. Similar reductions occurred in the osteoblastic osteoid (18 +/- 3 to 9 +/- 2 percent; P less than 0.01) and the degree of marrow fibrosis (6.2 +/- 1.7 to 3.5 +/- 1.3 percent; P = 0.01). Concomitant serum biochemical changes included increased calcium levels (2.55 +/- 0.03 to 2.67 +/- 0.05 mmol per liter; P less than 0.01), decreased alkaline phosphatase levels (489 +/- 77 to 184 +/- 32 U per liter; P less than 0.001), and decreased levels of PTH (amino-terminal, 172 +/- 34 to 69 +/- 16 ng per liter in five patients, P less than 0.03; and carboxy-terminal, 1468 +/- 467 to 1083 +/- 402 ml-eq per liter in six patients, P not significant). Although the majority of the patients had transient episodes of asymptomatic hypercalcemia, this complication could be quickly reversed by temporarily halting treatment or decreasing the dose of calcitriol. We conclude that long-term intermittent infusions of intravenous calcitriol are effective in ameliorating osteitis fibrosa in patients on dialysis. Patients whose osteitis fibrosa is refractory to oral calcitriol and who are candidates for parathyroidectomy should be considered first for intravenous calcitriol therapy.

Transplantation of Cadaveric Kidneys from Patients with Hepatorenal Syndrome

Abstract A kidney from each of five patients and both kidneys from a sixth patient dying with the hepatorenal syndrome (severe hepatic failure, oliguria, azotemia, hyponatremia and a urinary sodium of less than 5 mEq per day) were transplanted into seven patients with end-stage kidney disease whose liver function was normal. Diuresis and improvement of renal function occurred in all but one recipient. Because of postoperative complications, two kidneys were removed after diuresis had occurred. Four transplanted kidneys achieved stable function for six months or longer, with creatinine clearances of 25, 42, 50 and 52 ml per minute. The hepatorenal syndrome is functional and potentially reversible.

Acute Interstitial Nephritis Due to Methicillin

Fourteen patients are described with a syndrome of methicillin-induced interstitial nephritis. In all patients severe renal dysfunction developed with an average peak serum creatinine of 8 mg/100 ml. An increased total peripheral eosinophil count was found in all patients. All patients had sterile pyuria and each of nine patients studied by Wrights stain of urine sediment had marked eosinophiluria. These findings are suggestive of methicillin-induced interstitial nephritis, although proteinura was a variable finding in our patients. Eight of 14 patients in our study received prednisone therapy for their interstitial nephritis, and the time lapse between maximal and final base line serum creatinine levels was statistically less in the prednisone-treated compared to the nontreated groups. Clinical manifestations of this syndrome are discussed, and the light and electron microscopic and immunofluorescent findings on renal biospy are described.

Skeletal Resistance to Parathyroid Hormone in Renal Failure: Studies in 105 Human Subjects

Abstract The effects of an infusion of parathyroid extract on serum calcium and urinary phosphate levels were evaluated in 105 individuals—normal persons, patients with renal failure, patients trea...

Aluminum Is Associated with Low Bone Formation in Patients Receiving Chronic Parenteral Nutrition

Patients treated with chronic total parenteral nutrition may develop metabolic bone disease. We evaluated 22 bone biopsy specimens from 16 patients. Compared with those of age- and sex-matched normal controls, these specimens had significantly higher osteoid area and lower total bone area and bone formation rate, as measured by double tetracycline labels. Aluminum was found in specimens from the 14 patients receiving casein hydrolysate but not in the two receiving amino acids as their nitrogen source. The reduced bone formation correlated inversely with the logarithm of the aluminum level. Aluminum was localized to the surface of mineralized bone; tetracycline uptake was absent at those sites. These bone findings are similar to those from aluminum intoxicated patients on hemodialysis. Both groups also have low parathyroid hormone levels. Thus, aluminum appears to be an important pathogenic factor in the osteodystrophy of patients receiving dialysis or total parenteral nutrition.

changes in serum and urinary calcium during treatment with hydrochlorothiazide: studies on mechanisms.

Studies were undertaken in man to evaluate the roles of volume depletion and of the parathyroid glands in mediating the changes in serum and urinary calcium which follow the administration of hydrochlorothiazide, 100 mg twice daily, for 4 days, 42 studies were carried out in 16 normal subjects, 9 patients with hyperparathyroidism, and 7 vitamin D-treated subjects with hypoparathyroidism. In six studies in normal subjects, daily sodium losses during thiazide administration were quantitatively replaced, and in six other studies the effect of equivalent sodium losses produced by furosemide was evaluated. Although the magnitude of sodium losses was similar in three groups during therapy with thiazides, urinary calcium fell and urinary phosphorus increased significantly only in normal subjects and those with hyperparathyroidism; no change occurred in patients with hypoparathyroidism. With the replacement of the thiazide-induced sodium losses by NaCl in normals, urinary calcium did not change as urinary sodium increased 4- to 5-fold. Furosemide administration produced similar sodium losses while urinary calcium remained at or above control levels. After correction for changes in plasma protein concentration caused by thiazide-induced hemoconcentration, mean levels of serum calcium were significantly increased only in subjects with hyperparathyroidism and vitamin D-treated patients with hypoparathyroidism. The results indicate that both depletion of extracellular fluid volume and the presence of the parathyroid glands are necessary for the decrease in urinary calcium in response to thiazide therapy. Both the reduction in urinary calcium and increase in urinary phosphate after the use of thiazides may be due, in part, to potentiation of the action of the parathyroid hormone on the nephron. The rise in serum calcium could be due to thiazide-induced release of calcium from bone into extracellular fluid, particularly in states where bone resorption may be augmented, i.e., vitamin D therapy or hyperparathyroidism.

Renal Artery Embolism: Clinical Features and Long-Term Follow-up of 17 Cases

Spontaneous renal artery embolism is not rare, but a correct diagnosis and appropriate treatment are often delayed. Clinical features and follow-up of 17 cases are reported. Cardiac disease or arrhythmias pre-existed in 16 patients. Initial symptoms included flank pain (seven cases), abdominal or chest pain alone (seven), and nausea and vomiting (eight). Fever (greater than or equal to 37.5 degree C) occurred in 10 cases and flank tenderness in only eight. Laboratory findings included leukocytosis, proteinuria, hematuria, and elevated levels of lactic dehydrogenase, serum glutamic-oxalacetic transaminase, serum glutamic-pyruvic transaminase, and alkaline phosphatase. Serum creatinine level exceeded 1.3 mg/dl in 88% and 4.0 mg/dl in 65%; four patients required dialysis. The diagnosis, made by scintiscan, arteriography, or both was often delayed. Renal embolization was bilateral in seven patients and unilateral in 10, with serum creatinine level above 4.0 mg/dl in five of the latter. Emboli to other organs caused early death; cardiovascular disease led to later death. With anticoagulants, renal function returned in patients surviving more than 1 month, even those with bilateral emboli. Thus, renal embolism is recognizable if the disease is considered, and a favorable outcome is common with long-term anticoagulants.

Magnesium, the Mimic/Antagonist of Calcium

Magnesium, the fourth most abundant metal in living organisms, is distributed in three major compartments in the body: 65 per cent in the mineral phase of skeleton, 34 per cent in the intracellular...