Low serum uric acid associated with weight loss, sarcopenia

In patients with low serum urate (SU) levels, sarcopenia and weight loss are common symptoms. According to a study published in Arthritis and rheumatology.1

“A number of observational studies have linked low SU levels to adverse effects such as dementia, Parkinson’s disease and early mortality,” the researchers explained. “These studies have raised the question of whether excessive urate lowering could have adverse consequences, and therefore some gout society guidelines have issued recommendations to be cautious with urate lowering therapy, which can delay or negate optimal gout control.However, it is important to note that SU levels are strongly and positively associated with obesity and nutritional status.

Data from the National Health and Nutrition Examination Survey (NHANES), between 1999 and 2006, were used to assess adult patients (≥ 20 years of age) using dual-energy x-ray absorptiometry body composition analyzes ( DXA) of the whole body as well as analyzes available. SU concentrations. Body composition was assessed using body mass index (BMI), lifetime maximum BMI, waist circumference, and age-specific, sex-specific appendicular lean mass index and breed (ALMI, kg/m2) and fat mass index (IMF, kg/m2) Z-scores. Associations between SU ​​and body composition were determined by logistic regression. Mortality was determined using the National Center for Health Statistics (NCHS) NHANES Public Use Linked Mortality Files. SU and mortality were assessed before and after adjusting for differences in body composition via Cox regression.

Low SU concentrations were defined as

More patients in the low SU group had lower ALMI Z scores (29%) compared to the normal SU group (16%, p=0.001). Additionally, low SU was associated with increased mortality before adjustments for body composition (HR (95% CI): 1.61 [1.14,2.28], p = 0.008). However, after adjusting for body composition and weight loss, the results were not significant (HR: 1.30 [0.92,1.85]p = 0.13).

Investigators were unable to more closely characterize the metabolic health of participants with low circulating urate, which limited the study. Additionally, although the NHANES is generally highly representative, the limited number of patients on urate-lowering therapies hampered the ability to determine specific associations between low SU levels and outcomes for people currently being treated with urate-lowering therapy. Long-term outcomes, such as dementia or cognitive decline, could not be examined. Future studies may be useful, especially in older populations. The historical weight loss measure used in this study was self-reported and did not indicate whether the weight loss was intentional or unintentional, which could have been helpful. However, previous research suggests that weight loss in older people is more likely to be unintentional.

“These observations suggest that the often observed epidemiological correlation between low SU and adverse health effects may be confounded,” the researchers concluded. “Investigators should be careful to consider confounders related to weight loss, sarcopenia, cachexia, frailty, and related conditions when interpreting associations between low SU levels and outcomes. long-term in population-based studies. »

Reference:

Baker JF, Weber DR, Neogi T, et al. Associations between low serum uric acid, body composition and mortality [published online ahead of print, 2022 Aug 16]. Rheumatol arthritis. 2022;10.1002/art.42301. doi:10.1002/art.42301

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