1. Gouty nephropathy
Persistent hyperuricemia, 20% have clinical manifestations of nephropathy. After several years or more, renal tubules and glomeruli can be damaged one after another, and a few develop uremia. The incidence of uric acid nephropathy is second only to gouty joint damage, and it is closely related to the course of disease and treatment. Studies have shown that urate nephropathy has nothing to do with the severity of gouty arthritis, that is, patients with mild arthritis may also have nephropathy, while patients with severe arthritis may not necessarily have renal abnormalities. There was mild unilateral or bilateral low back pain in the early stage, followed by mild edema and moderate hypertension. Urine is acidic, accompanied by intermittent or persistent proteinuria, generally not more than++. Almost all of them have decreased renal tubular concentration function, resulting in nocturia, polyuria and low relative density of urine. After about 5- 10 years, the nephropathy worsened, and then developed into uremia, and about 17%-25% died of renal failure.
2. Urinary calculi
The urine of gout patients is acidic, so the concentration of uric acid in urine increases. Smaller stones are excreted with urine, but they are often not felt. Tiny brown sand grains can be seen in urine sediment. Larger stones can block the ureter and cause hematuria and renal colic, and secondary infection becomes pyelonephritis due to poor urine flow. Huge stones can cause deformation of renal pelvis and calyx and hydronephrosis. Simple uric acid stones do not develop on X-ray, but when sodium urate has calcium salt, stone shadows can be seen on X-ray.
3. Acute obstructive nephropathy
The obvious increase of uric acid in blood and urine is due to the extensive obstruction of renal tubules caused by a large number of uric acid crystals. Gout is often accompanied by hypertension, hyperlipidemia, arteriosclerosis, coronary heart disease and type 2 diabetes. Among the causes of gout death in the elderly, cardiovascular factors far exceed renal insufficiency. But there is no direct causal relationship between gout and cardiovascular disease, both of which are related to obesity and dietary factors.
4. Nodular tumor
Also known as gout nodule, it is a white crystal precipitated in a certain part of the body due to the excessive increase of blood uric acid and exceeding its saturation. Just like the amount of salt in a glass of salt water exceeds a certain limit, white precipitate will appear at the bottom of the glass. Where precipitated crystals are deposited, stones will appear. In patients with gout, tophi can be formed in almost all tissues except the central nervous system.
Some tophi are invisible to the naked eye, but white needle-like crystals can be seen under a polarizing microscope. These tiny crystals can induce the onset of gouty arthritis, and can also cause the destruction of articular cartilage and bone, fibrosis of surrounding tissues, and lead to chronic joint swelling and pain, stiffness and deformity, and even fractures. Some tophi are deposited on the body surface, such as around the helix and joints, which we can see with the naked eye. There are also some tophi deposited in the kidney, causing kidney calculi and inducing renal colic.