Clinical practice guideline for renal hypouricemia (1st edition)

Abstract

Renal hypouricemia (RHUC) is a disease caused by dysfunction of renal urate reabsorption transporters; however, diagnostic guidance and guidelines for RHUC have been lacking, partly due to the low evidence level of studies on RHUC. This review describes a world-first clinical practice guideline (CPG) and its first version in English for this condition. It was developed following the "MINDS Manual for Guideline Development" methodology, which prioritizes evidence-based medicine. It was published in Japanese in 2017 and later translated into English. The primary goal of this CPG is to clarify the criteria for diagnosing RHUC; another aim is to work towards a consensus on clinical decision-making. One of the CPG's unique points is that it contains textbook descriptions at the expert consensus level, in addition to two clinical questions and recommendations derived from a systematic review of the literature. The guidance shown in this CPG makes it easy to diagnose RHUC from simple blood and urine tests. This CPG contains almost all of the clinical foci of RHUC: epidemiology, pathophysiology, diagnostic guidance, clinical examinations, differential diagnosis, and complications, including exercise-induced acute kidney injury and urolithiasis. A CPG summary as well as a clinical algorithm to assist healthcare providers with a quick reference and notes from an athlete for both physicians and patients are included. We hope that this CPG will help healthcare providers and patients to make clinical decisions, and that it will promote further research on RHUC.

Keywords: Acute renal failure with severe loin pain and patchy renal ischemia after anaerobic exercise (ALPE); Clinical practice guideline (CPG); Evidence-based medicine (EBM); Exercise-induced acute kidney injury (EIAKI); Renal hypouricemia (RHUC).

Fig. 1

Clinical algorithm for renal hypouricemia (RHUC). If physicians detect a low serum uric acid (SUA) level, they should examine whether the patient’s SUA is lower than 2 mg/dl (120 µmol/l) or not. If it is, the physicians should reexamine the patient’s SUA level, because it sometimes varies according to their condition, and also test their urinary excretion of uric acid. Using these clinical data, diagnosis of RHUC is made along with the diagnostic guidance shown in Table 1. Physicians should treat patients appropriately if they suffer complications of RHUC, such as exercise-induced acute kidney injury (EIAKI) or urinary stones. If they do not have such complications, physicians should advise them that they are at risk of these complications and should therefore take action to prevent them. Because some mild RHUC patients show an SUA of 2.1–3.0 mg/dl, physicians should retest their SUA level and asking if there is a familial history of RHUC