Improvement of growth hormone response to stimulation in primary aldosteronism with correction of potassium deficiency

Heart failure as a risk factor for osteoporosis and fractures

Although heart failure (HF) and osteoporosis are common diseases, particularly in elderly populations, patients with HF have an increased risk for osteoporosis. The relationship of HF with osteoporosis is modified by gender and the severity of HF. In addition, shared risk factors, medication use, and common pathogenic mechanisms affect both HF and osteoporosis. Shared risk factors for these 2 conditions include advanced age, hypovitaminosis D, renal disease, and diabetes mellitus. Medications used to treat HF, including spironolactone, thiazide diuretics, nitric oxide donors, and aspirin, may protect against osteoporosis. In contrast, loop diuretics may make osteoporosis worse. HF and osteoporosis appear to share common pathogenic mechanisms, including activation of the renin-angiotensin-aldosterone system, increased parathyroid hormone levels, and/or oxidative/nitrosative stress. HF is a major risk factor for mortality following fractures. Thus, in HF patients, it is important to carefully assess osteoporosis and take measures to reduce the risk of osteoporotic fractures.

Aldosterone stimulates gene expression of hepatic gluconeogenic enzymes through the glucocorticoid receptor in a manner independent of the protein kinase B cascade

Primary aldosteronism is associated with glucose intolerance and diabetes, which is due in part to impaired insulin release caused by reduction of potassium, although other possibilities remain to be elucidated. To evaluate the in vivo effects of aldosterone on glucose metabolism, a single dose of aldosterone was administered to mice, which resulted in elevation of the blood glucose level. In primary cultured mouse hepatocytes, the gene expression of gluconeogenic enzymes such as glucose-6-phosphatase (G6Pase), fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase increased in response to aldosterone in a dose-dependent manner even at a concentration similar to a physiological condition (10(-9) M). The inhibitory effect of insulin on G6Pase gene expression was partially suppressed by aldosterone. Furthermore, aldosterone enhanced G6Pase promoter activity in human hepatoma cell line HepG2, which was prevented by co-treatment with a glucocorticoid antagonist RU-486, but not a mineralocorticoid antagonist spironolactone. In contrast, aldosterone had no effects on major insulin signaling pathways including insulin receptor substrate-1, protein kinase B, and forkhead transcription factor. These results suggest that aldosterone may affect the inhibitory effect of insulin on hepatic gluconeogenesis through the glucocorticoid receptor, which may be one of the causes of impaired glucose metabolism in primary aldosteronism.

Hyperglycemic crises in diabetes mellitus type 2

Hyperglycemic crises in type 2 diabetes are not rare and are becoming increasingly recognized as part of the spectrum of the presentation of previously undiagnosed diabetes mellitus and the decompensation of established diabetes mellitus. Contributing factors and associations are being elucidated but remain far from clear, particularly in DKA states. Medications commonly used in the treatment of many comorbid illnesses in patients with diabetes can themselves predispose to HHS. Endocrinopathies can contribute to insulin resistance and directly increase the glycemic load, leading to hyperglycemia. Medications such as the protease inhibitors may in the future lead to a better understanding of the pathophysiology of the metabolic derangements seen in the development of type 2 diabetes mellitus.

Hyperglycemia, lumbar plexopathy and hypokalemic rhabdomyolysis complicating Conn's syndrome

BACKGROUND

Lumbosacral plexopathy is a complication of diabetes mellitus. Conn's syndrome from an aldosterone secreting adenoma may be associated with hypokalemia and rhabdomyolysis but mild hyperglycemia also usually occurs.

METHODS

Case description.

RESULTS

A 70-year-old male diagnosed as having Conn's syndrome, hypokalemia and mild hyperglycemia developed rhabdomyolysis and lumbar plexopathy as a presenting feature of his hyperaldosteronism. His rhabdomyolysis rapidly cleared following correction of hypokalemia but recovery from the plexopathy occurred slowly over several months. Definite resection of the aldosterone secreting adenomas reversed the hyperglycemia.

CONCLUSIONS

Our patient developed lumbar plexopathy resembling that associated with diabetes mellitus despite the presence of only mild and transient hyperglycemia.

Increased insulin sensitivity in patients with aldosterone producing adenoma

OBJECTIVE

Primary aldosteronism is a recognized endocrine cause of glucose intolerance. A blunted insulin response to glucose in patients with primary aldosteronism is well known, but insulin sensitivity has not been thoroughly determined. We investigated insulin sensitivity and insulin secretion in patients with aldosterone producing adenoma.

DESIGN

Glucose tolerance and insulin responses to glucose were evaluated using a standard 75 g oral glucose tolerance test in patients with aldosterone producing adenoma before and after surgery, and in control subjects. Parameters for insulin resistance (HOMA-R) and pancreatic beta-cell function (HOMA-beta F) were derived from a homeostasis model assessment.

PATIENTS

Fifteen patients with aldosterone producing adenoma and 41 control subjects with normal glucose tolerance matched for age and body mass index, were studied. Eight patients were re-evaluated after surgical removal of the adenoma. In 5 patients 125I-insulin binding to erythrocytes was also measured.

MEASUREMENTS

Plasma glucose was measured by a glucose oxidase method. Plasma insulin, aldosterone and renin activity were measured by radioimmunoassay.

RESULTS

Both fasting plasma glucose and insulin were lower in the patients than in the controls. Although the areas under the curve for plasma glucose during the oral glucose tolerance test did not differ, that for plasma insulin was less in the patients with hyperaldosteronism. Insulin sensitivity was increased in the patients, as evidenced by decreased HOMA-R compared with controls, while HOMA-beta F was comparable between the groups. 125I-insulin binding to erythrocytes was higher in 5 patients than in 19 normal controls. After surgical removal of adenoma, neither fasting plasma glucose nor the glucose area under the curve during the oral glucose tolerance test changed. However, fasting plasma insulin and the insulin area under the curve increased significantly. HOMA-R increased and HOMA-beta F remained unaltered.

CONCLUSION

Insulin sensitivity was increased in untreated patients with aldosterone producing adenoma. Enhanced insulin receptor binding may contribute to this increased insulin sensitivity.

Dietary potassium influences kidney maintenance of serum phosphorus concentration

In studying the metabolic effects of diet potassium (K+) variation in normal humans, we noted that varying diet K+ within its normal range influenced inorganic phosphorus (Pi) homeostasis and serum calcitriol (1,25-dihydroxyvitamin D) levels. In six men who ingested a constant whole-foods diet containing (per 70 kg body wt) 27 mmol/day Pi and 52 mEq/day K+, we increased diet K+ to 156 mmol/day with supplements first of potassium bicarbonate (KHCO3) alone and then of potassium chloride (KCL) alone, each for eight days interrupted by an eight-day recovery period of no K+ supplement. Urine Pi decreased promptly with either K(+)-salt, each inducing a persisting retention of 7 to 10 mmoles Pi, which was dumped during recovery. Fasting serum [Pi] increased with either K+ supplement (P = 0.022, repeated measures analysis of variance); the composite mean serum [Pi] for the two K(+)-supplement periods exceeded that for the two periods without supplements (P less than 0.01, paired t-test). Conversely, the concentrations of serum calcitriol decreased with either K+ supplement (P = 0.020). Among subjects, the diet K(+)-induced increases in serum [Pi] correlated with those in plasma [K+] (r = 0.64, P = 0.027); the decreases in serum calcitriol concentration correlated with the increases in serum [Pi] (r = -0.69, P = 0.014). There were no significant differences among periods in serum parathyroid hormone, ionized calcium, urine cyclic AMP excretion, plasma renin activity, body weight, serum albumin, or creatinine clearance; plasma volume decreased slightly during KCL but not during KHCO3 periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of diuretic-induced secondary hyperaldosteronism and hypokalemia by trilostane, an inhibitor of adrenal steroidogenesis

Correction of diuretic-induced hypokalemia is usually accomplished by potassium supplementation or antagonism of aldosterone's renal action. This study sought to determine if inhibition of aldosterone biosynthesis could reverse diuretic-induced hypokalemia and whether trilostane would be clinically useful in this regard. Essential hypertensives (n = 22) were treated with hydrochlorothiazide (HCTZ) 50 mg/d, and patients who became hypokalemic were randomly assigned to receive in addition to HCTZ either a placebo (n = 7), trilostane 240 mg/d (Trilo 240) (n = 7), or trilostane 60 mg/d (Trilo 60) (n = 3). Following 12 weeks of therapy the placebo patients remained hypokalemic with hyperaldosteronism, while the patients who received Trilo 240 had a correction of hypokalemia and hyperaldosteronism (P less than .05) along with a reduction in diastolic blood pressure (P less than .05). The Trilo 60 patients, however, remained hypokalemic with no significant reduction in aldosterone excretion or blood pressure compared with HCTZ. Body weight and urinary free cortisol levels along with routine biochemical tests were unchanged during this study. Three Trilo 240 patients developed diarrhea but did not discontinue the study. These results demonstrate that trilostane can correct diuretic-induced hypokalemia by lowering aldosterone secretion. Furthermore, this reduction in aldosterone may enhance the antihypertensive effects of diuretic therapy.

Reversal of diuretic-induced secondary hyperaldosteronism and hypokalemia by enalapril (MK-421): a new angiotensin-converting enzyme inhibitor

The study reported here prospectively evaluated the prevention of diuretic-induced secondary hyperaldosteronism and hypokalemia by a converting enzyme inhibitor, enalapril (MK 421). Eighteen normal subjects were randomized into three groups: (1) a HCTZ group (hydrochlorothiazide (HCTZ) 50 mg/day); (2) a MK-421 group (MK-421 10 mg/day); and (3) a HCTZ + MK-421 group [HCTZ 50 mg/day plus MK-421 10 mg/day]. Following a five-day control and a 28-day treatment period, the HCTZ group demonstrated an attenuated but persistent secondary hyperaldosteronism and hypokalemia, the MK-421 group manifested a gradual decline in aldosterone secretion, and the HCTZ + MK-421 group had a delayed but effective correction of secondary hyperaldosteronism and hypokalemia at 28 days but not before. In conclusion, MK-421 reversed diuretic-induced secondary hyperaldosteronism and hypokalemia after 28 days of hydrochlorothiazide therapy. Therefore, converting enzyme inhibitors, such as enalapril, provide useful adjunctive therapy in diuretic-treated patients, but potassium supplementation may be required before the start of four weeks of combined therapy.

The therapeutic use of a new potassium-sparing diuretic, amiloride, and a converting enzyme inhibitor, MK-421, in preventing hypokalemia associated with primary and secondary hyperaldosteronism

This presentation is a summary of our recent clinical studies on the therapeutic use of a new potassium-sparing diuretic, amiloride, and a converting enzyme inhibitor, MK-421, in preventing hypokalemia associated with primary and secondary hyperaldosteronism. These drugs are quite different in their physiologic action but they both may be effective in preventing the potassium depletion associated with increased aldosterone production. Amiloride, which blocks the sodium channels in distal renal tubular cells, was administered to 10 patients with primary hyperaldosteronism and five patients with Bartter's syndrome (secondary hyperaldosteronism). Amiloride, at doses of 10-40 mg/day, increased mean plasma potassium levels in both primary hyperaldosteronism (3.2-4.5 mEq/L) and, to a lesser extent, in Bartter's syndrome (2.5-3.6 mEq/L). The blood pressure fell slightly but significantly in primary hyperaldosteronism (171/112 vs 150/97 mm Hg) and remained unchanged in Bartter's syndrome (116/80 vs 117/71 mm Hg). The plasma renin activity and plasma aldosterone rose in primary aldosteronism (PRA 0.39-2.21 ng A1/m1/h and PA 28.4-54.3 ng/d1); but in Bartter's syndrome, the PRA declined (25.3-11.9 ng A1/m1/h) and the PA rose (19.5-38.0 ng/d1). The discrepancy in the PRA between primary aldosteronism and Bartter's syndrome may be due to the effects of potassium repletion on suppressing renin and stimulating aldosterone; while in primary aldosteronism, a mild diuretic effect could explain the rise in PRA. In both of these disorders, despite the rise in plasma potassium levels, amiloride produced a counter-therapeutic rise in PA which could potentiate further potassium losses. Therefore, we undertook a study to evaluate the prevention of diuretic-induced hypokalemia and secondary hyperaldosteronism using a new converting enzyme inhibitor, MK-421. Eighteen normal subjects were randomized into three groups receiving either (1) hydrochlorothiazide alone (50 mg/day), (2) MK-421 alone (10 mg/day), or (3) hydrochlorothiazide (50 mg/day) plus MK-421 (10 mg/day). Although MK-421 did not prevent diuretic-induced hypokalemia or hyperaldosteronism in the first week, after that time hypokalemia was reversed and ASR returned to normal. In these studies, it therefore appears that while potassium-sparing diuretics may remain the medical mainstay in treating primary aldosteronism, new converting enzyme inhibitors such as MK-421 may be more effective in treating secondary hyperaldosteronism, since potassium levels can be normalized without increasing aldosterone secretion.

Proinsulin and C-peptide in diabetes

The availability of C-peptide measurement continues to provide new and useful information about the state of beta cell secretory function and the natural history of diabetes. Measurement of proinsulin is of value in the diagnosis of insulin-secreting tumors.

Hyperosmolar nonketotic coma in the elderly diabetic

The gravity of this syndrome of severe diabetic stupor without ketosis may not be recognized because patients are usually middle-aged or elderly with mild diabetes. A lack of urgency in treating these patients is probably the cause of the widely reported mortality of 40 to 70 per cent.

The diagnosis of diabetes: how to determine which patients to treat

The diagnosis of diabetes depends on identifying a compatible clinical picture with confirmation by demonstrable abnormalities in blood glucose levels. In florid diabetes, classical symptoms of diabetes and high glucose in blood and urine make the diagnosis easy. For asymptomatic diabetes; if confirmed fasting blood glucose measures over 125 mg per 100 ml, the diagnosis is accepted. When the fasting blood glucose measures under 125 mg per 100 ml, I recommend an oral glucose tolerance test and apply suitable criteria for interpretation. The United States Public Health Service criteria represent a reasonable, moderate approach when one modifies the interpretation by cognizance of environmental factors in the patient and by identifying interfering influences as drugs, physical inactivity, fever or starvation. Indeed, one should postpone a glucose tolerance test until these interfering factors abate. Management of the patient with an abnormal glucose tolerance test includes sharing the prognostic dilemma with the patient regarding the likelihood of deterioration in glucose tolerance to florid diabetes. In this situation the term, abnormal glucose tolerance test, is preferred over chemical diabetes. The physician and the patient must develop some degree of comfort with a clinical state that often remains nebulous. Though the writings of authorities occasionally sound dogmatic, rigid, and conflicting, they reflect a viewpoint which opines that no clear answers are available; that the clinician and his patient must accept this posture; and that together they must develop the best therapeutic program for the individual in question.

Pathophysiology of diabetes mellitus

Techniques have been developed for examining the binding of insulin to its target cells and for evaluating the in vivo action of insulin, rekindling interest in the possible role of insulin resistance in adult-onset diabetes. A host of new data have accumulated regarding the contribution of glucagon to the syndrome.