Donald J. Sherrard

Effects of dietary caffeine on renal handling of minerals in adult women

Thirty-seven women, aged 31-78 years, on two separate mornings consumed a decaffeinated beverage to which 6 mg caffeine/kg lean body mass or no caffeine were added. Total urine output of water, calcium, magnesium, sodium, chloride, potassium and creatinine increased in the two hours following caffeine ingestion when compared to the control beverage. Increased urinary mineral (mg)/urinary creatinine (g) ratios were seen for calcium (120 to 200), magnesium (70 to 110), sodium (3,800 to 6,200) and chloride (9,200 to 14,800), following the caffeinated beverage. Creatinine clearance did not change significantly. The percent reabsorption of calcium (98.6% to 97.5%, p less than .001) and magnesium (97.0% to 94.2%, p less than .0001) decreased significantly during the post-caffeine period. The calcium and magnesium filtered loads did not differ significantly between the caffeine and no caffeine beverages. Therefore, caffeine-induced urinary loss of calcium and magnesium is largely attributable to a reduction in calcium and magnesium renal reabsorption, although the physiological mechanism and tubular segment affected remain to be established.

Precipitation of Dialysis Dementia by Deferoxamine Treatment of Aluminum-Related Bone Disease

Five patients with chronic renal failure, complicated by bone aluminum toxicity, were treated with deferoxamine (DFO). This treatment appeared to precipitate dialysis dementia, which was fatal in three patients. In two patients, continuous treatment with lower doses of DFO was possible. The development of dialysis dementia in chronic renal failure patients with very high serum aluminum levels may be a complication of DFO treatment.

Secondary hyperparathyroidism complicated by parathyromatosis

Secondary hyperparathyroidism is a common complication of chronic renal disease. Clinical signs and symptoms tend to be severe and often are not controlled with medical measures. When medical therapy fails, parathyroidectomy becomes necessary. Recurrent hyperparathyroidism is not uncommon following surgery. One cause of surgical failure is parathyromatosis, which has been described as multiple nodules of hyperfunctioning parathyroid tissue scattered throughout the lower neck, superior mediastinum, or the arm if autotransplantation has been performed. Five cases of parathyromatosis in patients with chronic renal failure were identified. Clinical characteristics, course, and prognosis of the patients are reported. All patients had evidence of renal osteodystrophy and complained of severe pruritus and bone and/or joint pain. Three of the five patients had evidence of soft tissue calcification, two complained of muscle weakness, two had multiple fractures, and two eventually died of complications resulting from parathyromatosis. In four of five cases, surgical and medical management were ineffective. The patients described illustrate the severe morbidity and mortality associated with the parathyromatosis in the setting of end-stage renal disease. The pathogenesis remains controversial. Although primary prevention appears to be the most effective means of avoiding this complication, it is mandatory that meticulous care be taken during surgical manipulation. If such measures fail, calcium supplementation, calcitriol, and phosphate restriction may be tried.

Septic Arthritis in Hemodialyzed Patients

Six episodes of septic arthritis involving 5 patients and eleven joints were documented in the last 7 years in a population receiving 450 patient-years of dialysis treatment. The same micro-organisms were often cultured simultaneously from the joint, blood and/or arteriovenous fistula, suggesting hematogenous spread. A tendency toward multiarticular involvement was also observed. Early diagnosis is mandatory to avoid severe joint damage. Since such patients have other potential causes of arthritis and periarticular pain not due to infection, it is important to culture the joint fluid promptly whenever the possibility of infection exists.

Peritoneal dialysis fluid as a source of hepatitis antigen.

An epidemic of HBsAg positive hepatitis involving the dialysis unit of the Seattle Veterans Administration Medical Center is described. 6 patients and 4 staff members were affected: there were four patient deaths. The source of HBsAg was identified as a chronic in-center peritoneal dialysis patient in whom both serum and peritoneal fluid were persistently HBsAg positive. Surveillance data documented heavy population exposure to HBsAg at the time of this patients presence in the dialysis setting. We have subsequently identified 2 other patients with HBsAg positive peritoneal effluent. Peritoneal dialysis of HBsAg positive individuals represents a significant risk for the transmission of HBsAg and clinical hepatitis.

Interactions between Dietary Calcium and Caffeine Consumption on Calcium Metabolism in Hypertensive Humans

Abnormal calcium metabolism has been implicated in human hypertension. Caffeine consumption may contribute to hypertension since it increases urinary calcium excretion. Nineteen hypertensive subjects (HTN) and nineteen age and gender matched normotensive controls (NTC) who habitually consumed at least 175 mg caffeine daily were studied before and after abstinence from all caffeine (CAF) consumption for 2 weeks. Caffeine abstinence (CAF-) increased fasting serum ultrafiltrable calcium in HTN and NTC, but not serum total calcium. Parathyroid hormone (PTH) levels decreased after CAF abstinence in 14 of 18 HTN subjects, including all seven subjects consuming less than 700 mg calcium daily. Three day dietary calcium intakes and 72 h urinary excretion of calcium were not different between CAF+ and CAF- or between HTN and NTC. A morning caffeine dose of 6 mg/kg lean body mass increased urinary Ca/creatinine ratios similarly for 2 h after beverage consumption in both HTN and NTC. Caffeine consumption stresses calcium metabolism in hypertensive individuals, especially those consuming less than 700 mg calcium daily.

The Role of Blood Pressure Regulation in Uremia

The risks of high blood pressure and the benefits of its control are well established in the nonuremic population.(1,2) Less well-controlled, older studies strongly support the benefits of blood pressure reduction in patients with moderate renal insufficiency.(3) There is little reason to doubt that treatment of hypertension is an important facet of the care of patients with end-stage renal disease. Indeed, attempts to prove this contention with studies that included a control group of untreated hypertensives would not be ethically defensible.