Triglyceride concentrations in primary gout and gout of chronic lead nephropathy

Association of serum uric acid concentration with components of pediatric metabolic syndrome: A systematic review and meta-analysis

Background:

Hyperuricemia is implicated in the pathogenesis of inflammatory diseases and metabolic disorders. Metabolic syndrome (MetS) in childhood is one of the most important causes of different noncommunicable diseases in adulthood. This study aimed to systematically review the association between serum uric acid (UA) concentration and components of pediatric MetS.

Materials and Methods:

In this meta-analysis and systematic review, related articles were gathered by searching English databases including PubMed, Web of Science, Scopus, and Google Scholar. We used the following keywords: uric acid, metabolic syndrome, hypertension, fasting blood sugar (FBS), hyperglycemia; the search was limited to English language and included observational and cohort studies performed among children or adolescents. Pooled relative risks (odds ratio [OR]) and corresponding 95% confidence interval (95% CI) were extracted. A random-effect model was used.

Results:

On the basis of 34 eligible studies, the pooled correlation between UA with metabolic components including FBS (r = 0.24, 95% CI = 0.09–0.40), fasting insulin (r = 0.26, 95% CI = 0.15–0.37), and hyperglycemia (r for triglyceride and UA = 0.23, 95% CI = 0.19–0.38) (r for high-density lipoprotein and UA = −0.28, 95% CI = −0.37 to −0.20) was statistically significant. The association of both diastolic blood pressure (DBP) and systolic blood pressure (SBP) was statistically significant with UA (r for SBP and UA = 0.34, 95% CI = 0.24–0.43; r for DBP and UA = 0.18, 95% CI = 0.11–0.25). The OR between risk of abdominal obesity with UA was statistically significant (OR = 2.62, 95% CI = 1.41–3.84).

Conclusion:

Serum UA concentration is associated with major components of the pediatric MetS. Its measurement and control should be underscored in at-risk children and adolescents.

Effect of visceral fat accumulation on uric acid metabolism in male obese subjects: visceral fat obesity is linked more closely to overproduction of uric acid than subcutaneous fat obesity

We investigated the relationship between uric acid (UA) metabolism and fat distribution in 36 obese men with a mean +/- SD age of 38 +/- 16 years and mean body-mass index (BMI) of 34 +/- 4 kg/m2. Subjects were divided into two groups: subcutaneous fat obesity (SFO) and visceral fat obesity (VFO), according to their abdominal fat distribution based on the results of computed tomography (CT). SFO was defined as having a ratio of visceral fat area (VFA) to subcutaneous fat area (V/S) of less than 0.4, and VFO was defined as having a V/S ratio > or = 0.4. The levels of serum total cholesterol (T-Chol), triglyceride (TG), and fasting plasma glucose (FPG), and the diastolic blood pressure (dBP) were significantly higher in the VFO group than in the SFO group. Serum UA levels were much higher in both the SFO and VFO groups than in the non-obese control group (492 +/- 107 and 474 +/- 90 v 309 +/- 48 micromol/L, respectively). The 24-hour urinary urate excretion (u-UA24h) and the UA clearance (Cua) to creatinine clearance (Ccr) ratio were significantly higher in the VFO group than in the SFO group (3.75 +/- 1.43 v 2.69 +/- 1.12 mmol/d, P < .05; and 5.9% +/- 2.0% v 3.6% +/- 1.7%, P < .001, respectively). The frequency of hyperuricemia was markedly higher in both the SFO and VFO groups compared with the control group (71% and 73% v 0%, respectively). Although the high serum UA level seemed to be related to low u-UA24h in 80% of SFO subjects with hyperuricemia, this was the case in only 10% of VFO subjects. While 44% of VFO subjects with hyperuricemia were designated as an overproduction type. These results suggest that the mechanism of hyperuricemia in obesity may be affected by the difference in body fat distribution and that the assessment of body fat distribution and types of hyperuricemia is crucial for the treatment of obese patients with hyperuricemia.

Lipoproteins in patients with isolated hyperuricemia

BACKGROUND

There have been described abnormalities in the lipoprotein profile of hyperuricemic patients, it has not been clarified wether these abnormalities are due to the hyperuricemia or to the dyslipema often associated to these patients. Our aim is to study the apolipoprotein profile in hyperuricemic patients without dyslipemia compared to a control population.

PATIENTS AND METHODS

30 hyperuricemic patients and 26 healthy controls. Measurements were of blood uric acid, total cholesterol, total triglycerides, creatinine, HDL-C, and VLDL cholesterol, triglyceride, Apo B, Apo CII and Apo CIII (1 and 2). Uric acid clearance and fractionated excretion were measured in 24 h. urine samples.

RESULTS

No significant differences were found between hyperuricemic and control patients in cholesterol, triglycerides and apo B in VLDL, or LDL and HDL cholesterol. The levels of apo B, Apo AI levels and apo CIII/apo CII were similar in the hyperuricaemic and controls.

CONCLUSIONS

There are two types of hyperuricaemic patients, one group associated to hyperlipideamia and would be included in the X Syndrome. The other group not associated to other metabolic abnormalities. Is important to distinguish between these two groups to define the prognosis of a given patient because the greater cardiovascular risk linked hyperuricaemic patients could be related to the association to others cardiovascular risks factors.

Variability of lipid phenotypes in hyperuricaemic-hyperlipidemic patients

We studied changes in the hyperuricaemia-associated lipid phenotypes of primary hyperuricaemic-hyperlipidemic patients, none of whom was obese, hypertensive or an alcohol drinker. The patients were monitored for three months during which they were placed on a strict diet. The results obtained showed that phenotype IIB was most frequently associated with hyperuricaemia, followed by phenotypes IV and IIA. Lipid phenotypes were found to change in most patients during the study, even though most of them remained hyperuricaemic-hyperlipidemic. We also determined apoprotein B in each determination and found that over half the patients possessed increased levels of this apolipoprotein. The results confirm that hyperuricaemia is not associated to a unique lipid phenotype since the phenotype of a given patient may change with time, even in the absence of propitiating external factors.

Relationship between hypertriglyceridemia and uric acid production in primary gout

The relationship between uric acid metabolism and lipid levels was analyzed in 148 male subjects with primary gout. The subjects were divided into three groups according to their alcohol consumption: heavy drinkers, moderate drinkers, and nondrinkers or mild drinkers. There was no correlation between urinary uric acid excretion and serum triglyceride (TG) levels in the heavy group, but a marginally significant correlation was shown in the moderate group (P less than .05), and a significant correlation was observed in the nondrinker or mild group (P less than .001). This relationship in the nondrinker or mild group was also found to be significant after adjustment for BMI and age by multiple regression analysis. Serum lipoproteins were analyzed by sequential preparative ultracentrifugation in 21 patients with primary gout who neither drank alcohol nor were obese; VLDL-TG level, but not the VLDL cholesterol level, was found to be significantly correlated with 24-hour urinary uric acid excretion. These results indicate that there is a close correlation between the degree of uric acid production, as judged by 24-hour urinary uric acid excretion, and lipoprotein TG metabolism when the influence of alcohol intake is excluded.

Serum lipids and lipoproteins in patients with primary gout

Serum lipid and lipoprotein values of 32 male patients suffering from gout were quantitated and compared with corresponding values of a random control group which did not differ significantly with regard to age, body weight index and socio-economic status. All patients were on therapy with allopurinol which lasted on average for 6 years. The most striking differences between patients and controls were the increased triglyceride and apo B values and the decreased HDL-cholesterol (HDL-C) and HDL-phospholipid (HDL-PL) values in the patient group. The values of total cholesterol, LDL-cholesterol, apo A-I and Lp (a) were not significantly different between patients and controls. The great differences in the ratios of apo B/LDL-C, apo A-I/HDL-C and apo A-I/HDL-PL values suggest that gout is connected with changes in the chemical composition of the major lipoprotein classes. In three normolipemic individuals who were treated for 3 weeks with allopurinol no changes in lipoproteins and apolipoproteins were apparent. The results are discussed in view of the atherosclerosis risk of patients suffering from gout.

Family study of lipid and purine levels in gout patients

A family study was performed to determine whether the hypertriglyceridaemia associated with gout is present in families of gout patients or due to the life style of the patient himself. The study revealed the expected hypertriglyceridaemia in gout patients; this was reflected by elevated serum levels of prebetalipoproteins and with reduction in the proportion of beta-lipoprotein. None of these abnormalities were seen in the first-degree relatives. Furthermore, the proportion of high-density lipoproteins was not significantly raised in gout patients.

Family study of lipid and purine levels in gout patients and analysis of mortality

A family study was performed to determine whether the hypertriglyceridaemia associated with gout is present in families of gout patients or simply due to their life-style. The study revealed hypertriglyceridaemia in gout patients, reflected by hyperprebetalipoproteinaemia and with reciprocal reduction in the proportion of beta-lipoprotein. These abnormalities were not seen in first-degree relatives. No definite increase in mortality was found from coronary or cerebrovascular disease in male gout patients after presentation to hospital or in their relatives. Families of hyperlipidaemic gout patients did reveal a slight increase in male coronary deaths although the significance of this finding was doubtful since some hypercholesterolaemia was found in these hyperlipidaemic families.

Mechanism and treatment of hypertriglyceridaemia in gout

Using the Intralipid lipid tolerance test we could not demonstrate any direct effect of serum triglyceride on uric acid or any influence of hyperuricaemia on triglyceride removal. This result supports previous studies suggesting that hyperuricaemia and hypertriglyceridaemia are linked through the association of obesity and alcohol excess rather than a direct cause and effect mechanism. It was possible to demonstrate significant reductions of serum triglyceride in patients with gout by reducing either their alcohol intake or body weight. Reduction of serum uric acid by probenecid had no effect on serum triglyceride or cholesterol. Similarly, allopurinol had no significant effect on serum triglyceride, but a significant fall of serum cholesterol was observed.

Adenine phosphoribosyltransferase deficiency: its inheritance and occurrence in a female with gout and renal disease

A deficiency of adenine phosphoribosyltransferase (APRT) enzyme activity to approximately 40% of normal has been found in erythrocytes from a young woman aged 24 years, who had suffered from recurrent gouty arthritis since 11 years of age. She also demonstrated considerable, although asymptomatic, renal impairment with a creatinine clearance of one-third normal. Her father had suffered from gouty arthritis but had a normal APRT activity; he was obese, had a high purine intake and was a regular beer drinker. The patient's mother was asymptomatic with a normal serum urate concentration, but demonstrated a similar reduction in APRT activity to that of her daughter. Eleven other asymptomatic members of the family also demonstrated a similar reduction in APRT activity in erythrocyte lysates. The pattern of inheritance was consistent with autosomal transmission. Concentrations of phosphoribosylpyrophospate (PRPP) in erythrocytes were within normal limits both in the subjects with deficient, and in those with normal, APRT activity. Partial purification of APRT enzyme from erythrocytes of the index case did not reveal any difference from the normal enzyme as far as Michaelis constants, heat stability, or mobility in polyacrylamide gel was concerned. No primary abnormality of lipoprotein metabolism was demonstrated either in the propositus or in other members of her family. Study of urate metabolism in the propositus indicated that, although urate production was within the normal range in absolute terms, there was increased incorporation of glycine into produced urate, usually taken as one index of de novo urate production. Impaired renal excretion of urate was also shown. Although detailed study of urate metabolism has not been undertaken in other family members with APRT deficiency, no conclusive relationship has yet been demonstrated between APRT deficiency and disordered urate metabolism.

Hyperlipidaemia in gout

Significant elevations of plasma triglyceride and free fatty acids levels were shown in 107 gouty patients, but no significant difference was found in plasma cholesterol and phospholipid levels as compared with control subjects. A positive correlation was found between plasma triglyceride and free fatty acids levels (r = 0.249, P less than 0.05) in gouty patients. The heavy drinkers with gout (15.9% of the patients) had significantly higher plasma triglyceride, free fatty acids and gamma-glutamyltranspeptidase levels than the moderate or non-drinking gouty subjects. These results suggested that excessive intake of alcohol may play an important role in inducing hyperlipidaemia in gout.

Relationship between hepatic morphology and clinical and biochemical findings in morbidly obese patients

This study was undertaken to determine the interrelations between clinico-biochemical parameters and hepatic morphology in markedly obese patients. One hundred and sixty-six women and 52 men comprise this series. There was a statistically significant association of carbohydrate metabolism disturbance with increasing age and corpulence and, in women, with hyperuricaemia and morphological alterations of the liver. Menstrual irregularities also correlated well with hepatic morphology. The livers frequently exhibited steatosis, but other morphological changes were mild. Compared with women, men had higher triglyceride values, more severe hepatic involvement, and poorer correlation of carbohydrate disturbances with hepatic histology. The results indicate a central role of the impaired carbohydrate utilization in the biochemical and hepatic alterations of obesity.