Crystals

Crystals in urine (crystalluria) are solid formations consisting of salts that may precipitate in the sediment due to changes in the chemical composition and pH of urine. Their presence is detected by microscopic examination of urine sediment and can be found both in healthy individuals and in various diseases. Main types of crystals and their significance:

• Urates – salts of uric acid, usually found in acidic urine. They have a rhomboid shape and yellowish or brownish color. Often associated with a meat-based diet and can color urine brick-red. Prolonged presence of urates may indicate risk of urolithiasis.
• Oxalates – salts of oxalic acid, found in normal and acidic urine. They have the shape of envelopes or octahedrons. Increased oxalates may indicate metabolic disorders and contribute to stone formation.
• Phosphates – salts of phosphoric acid, usually detected in alkaline urine. They may appear as granules, plates, or needles. Excess phosphates are associated with urinary tract infections and metabolic disturbances.
• Cystine crystals – hexagonal plates, found in hereditary amino acid metabolism disorders (cystinuria) and increase the risk of stone formation.
• Crystals of other amino acids (tyrosine, leucine) – found in severe metabolic disorders and liver diseases.

Causes of crystalluria may include changes in urine pH, dehydration, urinary tract infections, metabolic disorders, certain medications, and dietary factors. Prolonged or significant detection of crystals requires medical consultation and additional examinations, including blood biochemical analysis, 24-hour urine collection, ultrasound of kidneys and urinary tract. Correction of crystalluria is done as part of treatment of the underlying disease and may include diet, medication, and lifestyle changes. Thus, microscopic examination of crystals in urine is an important diagnostic tool to assess the risk of urolithiasis and detect metabolic disorders.