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Biomedical subjects

M F Michelis

Publications and source records attributed to M F Michelis.

At least 19 recordsLinked to original sources
PubMed1998

Renin-aldosterone system can respond to furosemide in patients with hyperkalemic hyporeninism.

Thirty-four patients (65.3+/-3.3 years of age, mean+/-SEM) with hyperkalemia (serum potassium >5.0 mEq/L) had measurement of their renin-aldosterone system. Nineteen patients (56%) had plasma renin activity (PRA) >1.5 ng/mL/h, which was not low, while 15 (44%) had PRA <1.5. Twelve of the 15 hyporeninemic hyperkalemic patients were studied to determine whether their renin-aldosterone system responded to 2 weeks of furosemide, 20 mg daily. Four were nonresponders: PRA averaged 0.3+/-0.1 ng/mL/h, and it did not increase with furosemide or respond to captopril before or after furosemide. Eight patients were responders: PRA averaged 0.6+/-0.2 ng/mL/h and increased with furosemide to 5.5+/-3.4 ng/mL/h. Captopril failed to increase PRA before furosemide, but PRA increased to 15.3+/-8.4 ng/mL/h after furosemide. Plasma aldosterone was low in both nonresponders and responders (3.5+/-1.2 ng/dL vs 5.8+/-2.5 ng/dL) and did not increase significantly with furosemide (4.3+/-1.7 ng/dL vs 8.7+/-2.5 ng/dL). Serum potassium did not fall and therefore did not limit the rise in aldosterone. Renin responders had greater body weight, were predominantly female (6/8 vs 2/4) and were more likely to have diabetes mellitus (7/8 vs 0/4). Plasma atrial natriuretic peptide (ANP) fell with furosemide in 8 of 8 responders and in 1 of the 2 nonresponders in whom it was measured. Neither group had suppressed plasma prorenin levels, indicating no suppression of renin gene expression. These results indicate that many hyperkalemic patients do not have suppressed PRA. Further, a majority of patients with suppressed PRA have high levels of ANP and can respond to diuretic therapy with a rise in PRA and a fall in ANP, suggesting physiologic suppression of the renin system by volume expansion. A minority of hyperkalemic patients with suppressed PRA had PRA that did not increase under these study conditions.

Adult↗
PubMed1998

Percentage body fat determination in hemodialysis and peritoneal dialysis patients: a comparison.

OBJECTIVE: To evaluate percentage body fat in hemodialysis (HD) and peritoneal dialysis (PD) patients. DESIGN: A prospective study of 20 HD patients and 20 PD patients. SETTING: Sol Goldman Renal Therapy Center, Lenox Hill Hospital, New York, NY; Baumritter Kidney Center Albert Einstein College of Medicine, Bronx, NY; Body Composition Unit, St Luke's Roosevelt Hospital, Columbia University, New York, NY. PATIENTS: Twenty HD (10 men, 10 women) patients, mean age 41.8 +/- 2.4 years and 20 PD (12 men, 8 women) patients, mean age 48.6 years +/- 3.0 years. INTERVENTION: This is a noninterventional study. PATIENTS signed consent to undergo dual-energy x-ray absorptiometry, total body potassium counting bioelectrical impedance analysis, total body water determination, and anthropmetric evaluation. MAIN OUTCOME MEASURES: Present and compare percentage body fat between HD and PD patients as determined by the methods used. RESULTS: Percentage fat is not different between HD and PD patients. Differences in absolute values of percent fat between techniques exist. CONCLUSION: HD patients and PD patients may be evaluated by the methods of body composition used. Percentage body fat will vary among techniques; therefore the same method should be used to follow a patient over time.

Absorptiometry, Photon↗
PubMed1997

Evaluation of plasma osmolality and hormone responses in elderly chronic hemodialysis patients with excessive interdialytic weight gain.

Elderly patients may exhibit changes in plasma hormone levels, as well as thirst disorders. Two groups of elderly hemodialysis patients were evaluated to determine if excessive interdialytic weight gain was related to differences in postdialysis plasma osmolality or postdialysis measurement of plasma renin activity, or plasma levels of angiotensin II (a dipsogenic hormone), aldosterone, and vasopressin. Patients mean age was 77.0 +/- 8.8 years and patients were divided into groups, I and II, with less than or greater than 2 kg interdialytic weight gain. Postdialysis plasma osmolality was similar in both groups of patients (309.3 +/- 2.3 vs. 309.6 +/- 2.4 mOsm/Kg, p = 0.8) and postdialysis AVP levels also were no different (2.7 +/- 0.6 vs. 2.1 +/- 0.2 pg/mL, p = 0.3). There was also no statistical difference between postdialysis angiotensin II and aldosterone levels in either group of patients. Plasma renin activity (PRA) was also not different in either group (2.3 +/- 1.1 vs. 0.43 +/- 0.1 ng/mL/hr, p = 0.1), but group I patients, with less than 2 kg weight gain, tended to exhibit higher PRA values perhaps reflecting proximity to their dry weight postdialysis. Since excessive fluid intake did not appear to relate to plasma osmolality and hormone levels studied, it might be suggested that excessive drinking could be due to excessive sodium intake associated with personal dietary habits or perhaps other as yet unmeasured factors.

Aged↗
PubMed1996

Comparison of five body-composition methods in peritoneal dialysis patients.

Body-composition assessment is an important method of evaluating nutritional status in peritoneal dialysis patients. Because body-composition measurement estimates have not been fully validated in this population, we assessed five body-composition methods in 30 well-dialyzed peritoneal dialysis patients. The techniques studied included bioelectrical impedance analysis, dual-energy X-ray absorptiometry, total-body potassium counting, and anthropometry by two techniques. The dialysis patients were matched for age, race, sex, height, weight, and body mass index with 29 healthy control subjects in our laboratory database. By 5 x 2 x 2 analysis of variance, significant differences were found between results by modality (P < 0.0001) as well as by sex, with women having an increased percentage of fat (P < 0.0001). However, there was no significant intermethod difference by condition (peritoneal dialysis or control). That is, although significantly different percentage fat values were found between the body-composition techniques, this variability was independent of whether the measurement was made on control or peritoneal dialysis patients. Despite the differences between modalities, all techniques were found to correlate significantly with each other (P < 0.01 or better for men and P < 0.001 or better for women). Our experience shows that these routine techniques for measuring body composition can be readily applied to stable peritoneal dialysis patients.

Absorptiometry, Photon↗
PubMed1996

Renal failure: why today's patients live better and longer.

The clinical courses of two older patients with progressive renal failure associated with hypertension are described. Their underlying disorders are similar, but there are stark contrasts between medical therapies available now and 50 years ago. Such advances include the development of antihypertensive drugs and antimicrobial medications that have reduced the incidence of renal failure. In addition, recombinant erythropoietin and calcitriol have decreased the morbidity associated with chronic renal failure. Finally, technologic breakthroughs in dialysis have made a once-fatal condition eminently treatable.

Acidosis↗
PubMed1993

Determining peritoneal dialysis prescriptions by employing a patient-specific protocol.

OBJECTIVE: To develop a formula that would permit a rapid and simple calculation of required dialysate volume needed to provide a predetermined daily creatinine clearance. DESIGN: Prospective study of peritoneal dialysis patients followed for 6 months. SETTING: A primary care teaching hospital in New York. PATIENTS: Twenty-six patients beginning peritoneal dialysis entered and completed the study. INTERVENTION: By employing each patient's measured peritoneal equilibration test (PET) and a standard clearance formula, a patient-specific treatment protocol (PSP) was calculated. The PET 2-hour D/Pcreat was used for continuous cycling peritoneal dialysis (CCPD) and the 4-hour D/Pcreat was used for patients on continuous ambulatory peritoneal dialysis (CAPD) to determine a PSP that would provide a minimum of 6 L of creatinine clearance daily. MAIN OUTCOME MEASURES: Patients were followed for 6 months to assess the ability of this approach of maintaining acceptable levels of blood urea nitrogen, creatinine, albumin, and hematocrit over the 6-month period of observation. RESULTS: Our study of 26 patients revealed that only 6 patients (23%) could be treated with the standard prescription of 8 L/day on CAPD. The remaining 77% of our patients required 9-13 L/day for CAPD and 12-21 L/day for CCPD. All patients were free of uremic symptoms and demonstrated acceptable biochemical parameters over a 3-6 month period of observation. CONCLUSIONS: A patient-specific protocol utilizing individually derived PET data provides an acceptable and easy to calculate initial treatment prescription for each patient that avoids the necessity for trial and error that has heretofore been employed.

Adult↗
PubMed1993

Perturbations in sodium balance. Hyponatremia and hypernatremia.

Perturbations of serum sodium concentration are the most common electrolyte abnormalities seen in clinical medicine. Patients may exhibit profound alterations in mental status or be asymptomatic. Appropriate diagnosis and treatment is essential to reducing morbidity from serum sodium abnormalities. This article reviews the etiology, symptoms, and treatment of hyponatremic and hypernatremic syndromes.

Diagnosis, Differential↗
PubMed1992

Sucrose ingestion following exercise: selected cardiovascular, hormonal, renal, and metabolic effects.

Carbohydrates, frequently consumed following exercise for glycogen resynthesis, have been shown to have other systemic effects in resting men. We examined the effects of postexercise sucrose (a disaccharide carbohydrate) ingestion on the renal, cardiovascular, and sympathetic nervous systems. Eight men consumed 1 l of water (W) or 1 l of a 200 g sucrose solution (S) following 1 hour of bicycle exercise at 70% heart rate reserve. Measurements were made during 2 hours of recovery. Heart rate and systolic blood pressure were elevated following S as compared to W (p < 0.009, p < 0.04, respectively). Diastolic blood pressure was lower after S (p < 0.04) and mean blood pressure did not differ between beverages. Plasma and urinary catecholamines decreased similarly after exercise regardless of treatment. After S insulin (p = 0.0019) and glucose (p = 0.0036) were increased but serum aldosterone (p = 0.0083) and potassium (p = 0.0285) responses were lower. No differences were observed for plasma renin activity. Urine volume and kaliuresis were less after S (p = 0.03, p = 0.03). A 24% increase in metabolic rate (p = 0.002) and increased respiratory exchange ratio (p = 0.02) after S were observed. Systemic effects of sucrose ingestion following exercise include cardiovascular, renal, endocrine, and metabolic changes.

Adult↗
PubMed1992

Assessment of renal osteodystrophy in hemodialysis patients.

We performed a prospective study of 30 patients undergoing chronic hemodialysis to determine which of 6 generally available diagnostic procedures provided the most useful information for the assessment of bone disease in hemodialysis patients. The 6 procedures were: routine biochemical measurements, N-terminal parathyroid hormone (N-PTH), radiographic analysis of hands and clavicles, bone density determination by dual photon absorptiometry (DPA), deferoxamine stimulation test, and iliac crest bone biopsy. Serum N-PTH was elevated in 83% of patients but was not significantly associated with abnormalities of other biochemical parameters. No significant relationship was demonstrated between biochemical data and radiographic findings or between biochemical data and bone density by DPA. All patients with abnormal DPA had an elevation of N-PTH; therefore, DPA did not reveal any unsuspected disease. Bone biopsies were done in 20 patients and findings in each were consistent with uremic osteodystrophy, including osteitis fibrosa cystica in 11 patients and aluminum-associated bone disease in 2 patients. Six patients had mixed disease, and 1 patient had osteoporosis. Despite 11 positive deferoxamine tests, bone biopsy revealed aluminum deposition in only 7 of these patients, suggesting extraosseous aluminum accumulation in the remaining 4. Evaluation of the positive and negative predictive accuracies of DPA, x-ray analysis, N-PTH levels, and aluminum bone deposition revealed that normal DPA or x-ray findings do not exclude bone disease, that N-PTH level is a good marker for secondary hyperparathyroidism, and that a negative deferoxamine test excludes aluminum-associated bone disease. Discriminant analysis also reinforced these conclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1990

Frequency of hyponatremia and nonosmolar vasopressin release in the acquired immunodeficiency syndrome.

The frequency and pathophysiology of hyponatremia were studied in the acquired immunodeficiency syndrome. Of 71 hospitalized patients surveyed retrospectively, hyponatremia was observed in 37 (52%). Of 48 patients studied prospectively, 27 (56%) were hyponatremic. In 16 hyponatremic patients, volume status; serum and urine osmolalities; renal, adrenal, and thyroid function; and plasma vasopressin levels were assessed. Urine osmolalities were inappropriately elevated (mean, 377 mmol/kg of water) relative to serum osmolalities (mean, 268 mmol/kg of water). Four patients had moderate renal insufficiency. Plasma vasopressin levels were elevated in 15 patients, with the highest levels seen in patients who died (median, 7.08 pmol/L). Hyponatremia of multiple etiologies occurred in a majority of inpatients with the acquired immunodeficiency syndrome, often following the administration of hypotonic fluids, and was associated with a 30% (8/27) short-term mortality.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Hyperkalemia in the elderly.

Physiologic and pathologic events that occur in patients as they grow older may result in distal renal tubular dysfunction, as well as decreased levels of plasma renin activity and plasma aldosterone. Such alterations result in a tendency toward hyperkalemia. A syndrome termed hyporeninemic hypoaldosteronism, associated with hyperkalemia, has been frequently described in elderly patients. The common occurrence of hyperkalemia in the elderly may be aggravated by the use of drugs that either further suppress renin and/or aldosterone or interfere with distal tubular potassium excretion. Some patients with hyporeninemic hypoaldosteronism respond to diuretic therapy. The recognition of the possible development of severe hyperkalemia in the elderly patient may avoid serious and even fatal complications of this electrolyte disorder.

Aged↗
PubMed1990

Systolic hypertension in the elderly: reasons not to treat.

Isolated systolic hypertension in the elderly is associated with increased morbidity and mortality. Accurate measurement of blood pressure in older patients is difficult. Therapy can be associated with various complications, and the special problems of the elderly, such as orthostatic hypotension and hyperkalemia, should be carefully considered. Drugs should be used in low doses and changes in dosage should be made infrequently. Patients should be monitored frequently for untoward effects of therapy. The benefits of blood pressure reduction and the optimal degree of blood pressure reduction remain unknown.

Aged↗
PubMed1987

The renin-angiotensin system is not responsible for hypertension following coronary artery bypass grafting.

Systemic hypertension following coronary artery bypass graft (CABG) procedures has been reported to occur in 15% to 80% of cases. Previous reports have implicated the renin-angiotensin system as being responsible, at least in part, for this phenomenon. In this prospective study, 18 previously normotensive subjects were studied before, during, and after CABG. In 4 patients (22%), paroxysmal postoperative hypertension developed (systolic blood pressure greater than 150 mm Hg). There were no differences between the normotensive and hypertensive groups in plasma renin activity, angiotensin II level, or aldosterone level. Despite the trend toward elevation of these variables during cardiopulmonary bypass (CPB), all had returned to control levels within two hours after CPB, whether or not hypertension developed. Serum norepinephrine levels were elevated (.10 greater than p greater than .05) in the hypertensive group at the time hypertension developed. No other relationship or pattern could be defined to distinguish the hypertensive from the normotensive group. The renin-angiotensin system does not appear to be responsible for paroxysmal hypertension following CABG.

Adult↗
PubMed1987

Increased levels of plasma renin, aldosterone, catecholamines and vasopressin in chronic ambulatory peritoneal dialysis (CAPD) patients.

Fluid excess can cause hyporeninemia and hypoaldosteronemia in hemodialysis patients. In six patients on CAPD, plasma renin activity (PRA) and plasma aldosterone (PA) were elevated to levels of : PRA 10.2 +/- 2.9 nl (1-5 ng/ml/h), and PA: 47.4 +/- 16.2 (normal 5-20 ng/dl). In 4 patients, data posthemodialysis and later during CAPD revealed that PRA increased from 0.9 +/- 0.3 to 14.1 +/- 4.6 and PA increased from 3.4 +/- 0.3 to 67.4 +/- 24.9 on CAPD (p less than 0.05). Mean arterial pressure was lower on CAPD and serum glucose was higher. No significant difference was seen in weight, hematocrit, BUN, or potassium, however. Plasma volume was not decreased in five CAPD patients: 3619 +/- 358 ml (predicted 3083 +/- 201 ml). Elevated catecholamine levels were seen in CAPD patients: norepinephrine 868.0 +/- 104.1 (normal 358.4 +/- 41.5 pg/ml), epinephrine 386.3 +/- 49.2 (normal 58.3 +/- 10.6 pg/ml). Plasma vasopressin levels were elevated to the range usually seen with hyperosmolality. In eight patients who lost or gained weight on CAPD, levels of PRA and PA changed as expected, but catecholamine levels did not correlate with weight changes. The data suggest that in CAPD patients, PRA and PA may be elevated in association with augmented sympathetic stimulation and elevated vasopressin levels. Serial observations demonstrated that PRA and PA can respond appropriately to changes in body weight, while catecholamine and vasopressin levels seem to be influenced by other factors.

Aldosterone↗