Expansion
Filtered, almost completely reabsorbed, then secreted, with net excretion about 10 per cent
Expansion
Urate undergoes filtration, extensive reabsorption (about 99 per cent, mainly by URAT1), then secretion, then further reabsorption. Net excretion is only about 10 per cent of the filtered load.
Raised by
- Volume depletion and any state increasing proximal sodium reabsorption: dehydration, diuretics
- Thiazide and loop diuretics
- Low dose aspirin, which inhibits secretion (high dose is uricosuric)
- Ciclosporin, pyrazinamide, ethambutol
- Lactate and ketones, which compete for secretion, so alcohol, starvation and diabetic ketoacidosis raise urate
- Increased production: purine-rich diet, tumour lysis, myeloproliferative disease
- Reduced GFR
Lowered by
- Probenecid, sulfinpyrazone and benzbromarone, which block reabsorption
- Losartan, uniquely among angiotensin receptor blockers, which is mildly uricosuric
- SGLT2 inhibitors
- Allopurinol and febuxostat, which reduce production rather than affecting the kidney
This explains why an acute gout attack is often precipitated by a diuretic, an illness with dehydration, or a binge.