A 74-year-old female consulted our hospital with pain and swelling of her right knee joint and deformity of both MP joints and PIP joints. Routine serum laboratory examinations revealed marked hypouricemia. Her serum uric acid level was 0.8mg/dl. We performed urate clearance test, benzbromarone test and pyrazinamide test to estimate urate transport in nephrons based on four-componentheory. Urate clearance (Cua) was increased (44.1ml/min) and urate excretion (Uua)was normal (0.41mg/kg/hr). Presecretory reabsorption rate, secretion rate and postsecretory reabsorption rate in nephrons were calculated to be 0.899 (normal controls ± standard errors of 14 subjects: 0.961±0.030),95.2(normal controls: 65.8±15.0)ml/min and 0.573 (normal controls: 0.882±0.019), respectively. The amount of urate transport in glomerular filtration, presecretory reabsorption, secretion, postsecretory reabsorption, and urinary excretion were estimated as 674 (nomal controls ± standard errors of 14 subjects: 7110±711) μg/min,606 (normal controls: 6840±786)μg/min,810 (nommal controls: 3710±935)μg/min,503(normal controls: 3530±711)μg/min, and 375(normal controls: 462±112)μg/min, respectively. These findings suggested that her hypouricemia was likely induced by increasing urate secretion rate and decreasing postreabsorption rate in nephrons. Urate transport abnormalities in hypouricemia as well as differential diagnoses of hypouricemia are discussed as well.

View full abstract

The Chiba Uric Acid Study group performed a questionnaire investigation by mail to 1769 physicians and orthopedists with the cooperation of the Chiba Medical Association. The goal was to identify current practices in management of gout and hyperuricemia in 2002before the announcement of a new “Guideline for the Managemen otf H yperuricemaian d Gout” by the Japanese Society of Gout Nucleic Acid Metabolism. A total of 338 medical doctors (19.1%) with an average age of 55.6 years old replied to the questionnaire. Seven mg/dl was the most common serum urate level used for the diagnosis of hyperuricemia (63%), and 8mg/dl for introduction of therapy for hyperuricemia (51%). The guideline classifies hyperuricemia into four types: overproduction (12%), renal underexcretion (60%), mixed (25%) and normal (3%), and guides the selection of medicine based on the pathophysiology of hyperuricemia H. owever, the vast majority (75%) did not classify by types, and 67.4% of medical doctors chose allopurinol, an inhibitor of production of uric acid. These data indicated that the popular treatment for hyperuricemia and gout in Chiba prefecture was not consistent with that recommended in “Guideline for the Management of Hyperuricemia and Gout”, and further training is necessary.

View full abstract

Purine nucleotide degradation is accelerated during strenuous exercise, and hypoxanthine (HX; p mol/L) increases in the plasma. In this study we determined purine degradation and sympathetic activation in subjects with varying degrees of exercise tolerance. Plasma HX (μmol/L), lactate (mmol/L), and norepinephrine (NE; ng/ml) were measured at cardiopulmonary exercise test in 41 controls,12 fit subjects, and 132 patients (NYHA 1: 47,11: 61,111: 24) with chronic heart failure (CHF). Peak VO2 decreased as CHF worsened (controls, Fit, CHF class I, II, III: 28.1±7.9,38.2±6.0,22.5±4.3,18.5±4.0,13.4 ±2.7 ml/min/kg, ANOVA p<0.0001). A Plasma HX (23.4±12.5,33.0±16.1,18.1±13.5,16.1 ± 8.9,9.6±3.7 p mol/L, ANOVA p<0.0001) and A blood lactate (5.1±2.0,6.7±1.8,4.2±1.7,3.8± 1.8,2.7 ±1.2 mmol/L, ANOVA p<0.0001)decreased according to the NYHA class. While A plasma NE was markedly higher only in fit subjects (2.19±1.61,5.25 ± 2.45,2.06±1.63,2.23±1.22,1.91 ± 1.02 ng/ml, ANOVA p<0.0001). In summary, purine degradation and lactate production were reduced as exercise capacity decreased, but exercise NE was markedly elevated in fit subjects. Thus, anaerobic markers decreased as heart failure worsened, suggesting that patients are unable to continue exercise in the anaerobic condition. Markedly elevated plasma NE in fit individuals suggests a potentially greater importance of high sympathetic activity for achieving a high level of exercise.

View full abstract