Management of hypertension and dyslipidaemia in patients presenting with hyperuricaemia: case histories

A number of studies have shown that hyperuricaemia is associated with an increased incidence of coronary heart disease. It has been proposed that the elevated serum uric acid levels are linked to other risk factors, such as hypertension, dyslipidaemia and diabetes. Hyperuricaemia is commonly encountered in patients with essential hypertension and is considered as a risk factor for morbidity and mortality associated with hypertension. In addition, lipid abnormalities (mainly hypertriglyceridaemia) are also found more frequently in hypertensive patients than in normotensives. There is evidence that the angiotensin II receptor antagonist, losartan, increases urate excretion by reducing reabsorption of urate in the renal proximal tubule. It is also known that fibric acid derivatives (fibrates) have several beneficial actions in addition to their lipid-lowering capacity. Fenofibrate administration is associated with a uric acid lowering effect. In this respect, we present two patients with hypertension and dyslipidaemia together with elevated serum uric acid levels. We also discuss (in the format of questions and answers) the pathophysiological mechanisms underlying the association of serum uric acid with cardiovascular disease, and we review the relevant literature to justify an evidence-based decision to choose an antihypetensive agent (losartan) or a lipid-lowering drug (fenofibrate) with an additional hypouricaemic effect.

The treatment of hypertension in patients with erectile dysfunction

Hypertension is another predictor of erectile dysfunction (ED). This is further evidence supporting a link between the pathogenesis of atherosclerotic disease and ED. In one study (TOMHS) involving hypertensive patients, the incidence of ED was 14.4%. The drugs used to treat hypertension may cause ED. However, there is little trial-based evidence to indicate which drugs are more likely to cause this side effect. In general, thiazide diuretics and beta-blockers seem to cause ED more often. In contrast, the alpha-blocker, doxazosin, has not been associated with an increased incidence of ED as a side effect. Doxazosin also improves urinary flow in patients with benign prostatic hyperplasia (BPH). This condition is common in elderly men as is hypertension and ED. Therefore, doxazosin may present a special advantage among this group of patients. This alpha-blocker would also be a good choice in patients with impaired glucose tolerance/diabetes because it improves insulin sensitivity. Moreover, ED and hypertension are more prevalent among diabetics. On a more speculative note, doxazosin may potentiate the therapeutic impact of specific treatments for ED.

Treatment of dyslipidaemias in patients with established vascular disease: a revival of the fibrates

The key 'statin trials' focussed on the beneficial effect of lowering the circulating concentrations of low-density lipoprotein cholesterol (LDL). However, epidemiological surveys, mainly based on healthy populations, indicate that other lipid-related variables, such as high-density cholesterol (HDL), triglycerides (TG), dense LDL subfraction distribution, and possibly lipoprotein (a) (Lp(a)), are also predictors of vascular events. Furthermore, TG and HDL levels influenced outcome within some of the statin trials. Plasma fibrinogen levels have also been shown to be powerful predictors of vascular risk in healthy subjects and patients with established ischaemic heart disease. The fibrates exert beneficial effects on all these variables that predict vascular events. The results from recent trials, the Bezafibrate Infarction Prevention (BIP) study and the Veterans Administration HDL Intervention Trial (VA-HIT) have revived our interest in fibrates. These trials involved bezafibrate and gemfibrozil that have a relatively poor LDL-lowering capacity. Therefore, the benefits reported in BIP and VA-HIT must be attributed to actions on variables other than a reduction in LDL quantity. Ciprofibrate and fenofibrate have significantly greater LDL-lowering capacity than bezafibrate or gemfibrozil. This advantage may render them more effective, especially since they retain the additional beneficial actions associated with this class of lipid-lowering drugs.

Acid-base and electrolyte abnormalities in patients with acute leukemia

Disturbances of acid-base balance and electrolyte abnormalities are commonly seen in patients with acute leukemia. Our study aimed at illuminating the probable pathogenetic mechanisms responsible for these disturbances in patients with acute leukemia admitted to our hospital. We studied 66 patients (24 men and 44 women) aged between 17 and 87 years old on their admission and prior to any therapeutic intervention. Patients with diabetes mellitus, acute or chronic renal failure, hepatic failure, patients receiving drugs that influence acid-base status and electrolyte parameters during the last month, such as corticosteroids, cisplatin, diuretics, antacids, aminoglycosides, amphotericin, penicillin, and K(+), PO(4)(3-), or Mg(2+) supplements were excluded. Forty-one patients had at least one acid-base or electrolyte disturbance. There were no significant differences in the incidence of acid-base balance and electrolyte abnormalities between patients with acute myeloid leukemia (AML) and patients with acute lymphoblastic leukemia (ALL). The most frequent electrolyte abnormality was hypokalemia, observed in 41 patients (63%), namely in 34 patients with AML, and 7 with ALL; the main underlying pathophysiologic mechanism was inappropriate kaliuresis. Furthermore, hypokalemic patients more frequently experienced concurrent electrolyte disturbances (i.e., hyponatremia, hypocalcemia, hypophosphatemia, and hypomagnesemia), as well as various acid-base abnormalities compared to normokalemic patients. Hypokalemia in patients with acute leukemia may serve as an indicator of multiple concurrent, interrelated electrolyte disturbances, especially in patients with AML.

Plasma and Lp(a)-associated PAF-acetylhydrolase activity in uremic patients undergoing different dialysis procedures

Plasma and Lp(a)-associated PAF-acetylhydrolase activity in uremic patients undergoing different dialysis procedures.

BACKGROUND

Platelet-activating factor (PAF) is a potent inflammatory mediator associated with several physiopathological conditions, including renal diseases. PAF is degraded to the inactive metabolite lyso-PAF by PAF-acetylhydrolase (PAF-AH), which is considered as a potent anti-inflammatory and anti-atherogenic enzyme associated with lipoproteins. In this study, we evaluated the plasma- and lipoprotein(a) [Lp(a)]-associated PAF-AH activity in relationship to plasma lipid parameters and Lp(a) isoform size in patients with mild/moderate chronic renal failure (CRF), as well as in hemodialysis (HD) and chronic ambulatory peritoneal dialysis (CAPD) patients.

METHODS

We studied 74 patients undergoing maintenance HD, 44 patients undergoing CAPD, 56 patients with mild/moderate CRF, and 98 healthy subjects whose lipid profile, as well as plasma and high-density lipoprotein (HDL)-associated PAF-AH activity, was determined. Moreover, the effect of Lp(a) plasma levels on the distribution of PAF-AH among plasma lipoproteins, as well as the specific activity and kinetic properties of PAF-AH on two different Lp(a) isoforms, was measured in each studied group.

RESULTS

The plasma PAF-AH activity in all studied groups was significantly higher than in controls, and the increase was more profound in CAPD patients. The HDL-associated PAF-AH activity, expressed per milliliter of plasma, was similar among all studied groups; however, when it was expressed as either per milligrams of HDL cholesterol or per milligrams of plasma apolipoprotein (apo) AI, the PAF-AH activity was significantly higher in all patient groups compared with controls. All patient groups had significantly elevated plasma Lp(a) levels, which altered the distribution of PAF-AH among the plasma lipoproteins compared with that observed in subjects with very low plasma Lp(a) levels (<8 mg/dl). Additionally, in each studied group, the specific activity as well as the apparent Km and Vmax values of the 19K4 apo(a) isoform were significantly higher (P < 0.01) compared with the values of the 23K4 isoform. However, the specific activity, as well as the Km and Vmax values on either the 19K4 apo(a) isoform or the 23K4 isoform, was significantly higher in CAPD patients compared with the other three groups.

CONCLUSIONS

Plasma PAF-AH activity is increased in uremic patients. This elevation is more profound in CAPD patients, who also exhibit a more atherogenic lipid profile and more pronounced alterations in the specific activity and the kinetic constants of Lp(a)-associated PAF-AH.

Prerenal azotemia in a diabetic patient with hyporeninemic hypoaldosteronism and autonomic neuropathy

Patients with hyporeninemic hypoaldosteronism show mild to moderate renal insufficiency, with a creatinine clearance of 20-75 ml/min, and asymptomatic hyperkalemia. A low degree of sodium wasting and mild hyperchloremic metabolic acidosis are also usually present. However, severe sodium wasting and volume depletion are not typically seen unless the patient is placed on severe sodium restriction or has some other cause of extrarenal sodium loss. In fact, acute renal failure has not been reported in such patients. We describe a diabetic patient with hyporeninemic hypoaldosteronism and autonomic neuropathy who developed recurrent episodes of acute renal failure due to prerenal azotemia during acute exacerbations of diarrhoea. In our case, despite significant hypovolemia, the renin-aldosterone axis was markedly suppressed, implying that sympathetic tone played a decisive role in renin regulation.

Apolipoprotein(a) phenotypes and lipoprotein(a) concentrations in patients with renal failure

Patients with renal failure have an increased incidence of atherosclerotic disease. Numerous studies have shown that these patients show increased serum lipoprotein(a) [Lp(a)] concentrations compared with the control population. However, variable alleles at the apolipoprotein(a) [apo(a)] gene locus determine to a large extent the Lp(a) concentration in the general population. We therefore undertook the present study to evaluate apo(a) phenotypes and Lp(a) serum concentrations in a large number of patients with renal disease. Seventy-nine patients treated by hemodialysis (HD), 47 patients treated by continuous ambulatory peritoneal dialysis (CAPD), 68 patients with mild/moderate chronic renal failure (CRF) and serum creatinine levels of 1.8 to 8 mg/dL, and 73 healthy controls were studied. All patients showed significantly elevated median serum Lp(a) concentrations in comparison with controls: HD patients, 15.7 mg/dL (P < 0.01); CAPD patients, 20 mg/dL (P < 0. 005); CRF patients, 15.1 mg/dL (P < 0.01) versus controls, 7 mg/dL. The greater Lp(a) values in all groups were not explained by differences in isoform frequencies, whereas their increase was apo(a)-type specific. Thus, patients in all groups with high-molecular-weight (HMW) apo(a) isoforms showed a significant elevation of Lp(a) levels, whereas serum Lp(a) concentrations in patients with low-molecular-weight (LMW) isoforms were not significantly different from controls, except for CAPD patients, who presented increased serum Lp(a) concentrations. We conclude that in patients with renal failure, even of mild/moderate degree, as well as in patients with end-stage renal disease undergoing HD or CAPD, elevated Lp(a) concentrations are mainly observed in those with HMW apo(a) phenotypes.

Electrolyte abnormalities in elderly patients admitted to a general medical ward

Elderly patients are particularly sensitive to the development of various electrolyte abnormalities, since they commonly exhibit some derangements in the physiologic homeostasis of acid-base status and electrolyte balance. Our study was undertaken to assess the prevalence, as well as the pathophysiologic mechanisms involved in the development of electrolyte abnormalities in 248 elderly patients admitted to our clinic for a variety of causes. Fifty-five out of these patients (22.2%) had at least one electrolyte abnormality. In such cases a thorough laboratory investigation was performed in an attempt to delineate the pathophysiologic mechanisms involved in relation to age.

Renal abnormalities in patients with sickle cell-beta thalassemia

We examined renal abnormalities in Greek patients with sickle-cell beta thalassemia (S-beta thal). A total of 17 patients aged 16-59 years suffering from S-beta thal and 17 age- and sex-matched healthy controls were studied. In all individuals we carried out a detailed study of renal function including electrolytes in serum and urine, concentrating or diluting ability, urine acidification ability, glomerular filtration rate (GFR), and hormones [such as plasma renin activity (PRA), serum aldosterone, and erythropoietin (EPO)]. Though the GFR did not differ significantly in patients and controls, half the patients had either supranormal or subnormal values. Serum potassium and uric acid were significantly higher in patients than controls. Serum phosphorus was similar in both groups, though patients with S-beta thal had significantly lower phosphate excretion indices. All patients were unable to maximally concentrate the urine, and seven also had limited ability to maximally dilute it. Five patients had incomplete distal renal tubular acidosis. Four had mild proteinuria, and six had microalbuminuria. Serum EPO and aldosterone were higher in S-beta thal patients than controls, but there was no difference in PRA between the two groups. There was a strong correlation between hemoglobin concentration and EPO levels, which was strongest in patients with GFR < 50 ml/min. We conclude that patients with S-beta thal, like sickle-cell anemia patients, present multiple abnormalities of renal function.