Abstract of kidney disease. Image of a woman in posterior view, showing nuts-and-bolts-filled kidneys superimposed on her lower back. The renal arteries and veins are seen branching to these kidneys. Nuts-and-bolts may represent kidney stones, hard stones formed by precipitation from solution of substances in the urine. They can block the kidneys and ureters, and may lead to kidney damage and pyelonephritis. Kidneys may also be affected by cysts, a disorder which is usually inherited. Tumours (some cancerous) may occur in the kidneys, but these are rare. Patients with diabetes may suffer impaired kidney function.