Manual of basic techniques for a health laboratory - libdoc.who.int

7. Examination of urine 247Fig. 7.29 Calcium sulfate crystalsFig. 7.30 Amorphous phosphatesFig. 7.31 Amorphous uratesFig. 7.32 Cystine crystalsThey are soluble in acetic acid, 10% solution (reagent no. 2) (one drop per drop ofdeposit).Amorphous urates (acid urine) (Fig. 7.31)Amorphous urates appear as very small, yellowish granules, which are grouped incompact clusters.They are not soluble in acetic acid, 10% solution (reagent no. 2), but dissolve if theurine is gently heated.(Urine kept in the refrigerator often shows a heavy precipitate of urates.)Other crystalline depositsThe following are rarely found in the urine. When present, however, they are foundin large quantities in patients with certain diseases.Cystine (acid urine) (Fig. 7.32)Size: 30–60mm.Shape: hexagonal plates.Colour: colourless, very shiny.Cystine crystals are found only in fresh urine as they are soluble in ammonia.They are found in patients with cystinuria, a very rare hereditary disease.Cholesterol (acid urine) (Fig. 7.33)Size: 50–100 mm.Shape: squarish plates, with notches on one side.Colour: colourless, shiny.Cholesterol crystals are found in the urine of patients with nephrotic syndrome.