A 24-hour urine test for kidney stones

It measures the day's urine volume and selected dissolved substances involved in crystal formation or protection against it. Clinicians often use the findings with stone analysis, blood tests, scans, diet, medicines, and your history of stone episodes.

Concentrated urine can allow minerals to come together more readily. The report may also show that certain stone-forming substances are high, or that protective substances are low. Urine acidity can favour some crystal types over others. None of these findings should be interpreted alone, because stone composition and medical context determine which changes are relevant.

The result may lead to advice about fluid intake, food choices, or medicine. Recommendations should target the measured pattern; severe restriction of a food group or excessive fluid intake without clinical guidance can create other problems.

Choose a reasonably typical day unless your clinic requests otherwise. Do not deliberately drink far more or less than usual, and do not alter medicines or diet simply to influence the result. At the recorded start time, urinate into the toilet; after that, collect every sample through the day and night, including the final one at the same time the next day.

Store the container exactly as the laboratory directs. If urine is missed or spilled, or the timing is wrong, contact the laboratory because restarting is often more informative than submitting a partial sample. Provide details of supplements, stone medicines, and any recent vomiting or diarrhoea that changed your usual intake.

Seek urgent assessment for severe or escalating flank or abdominal pain, especially with fever, chills, repeated vomiting, or feeling very unwell. Inability to pass urine, markedly reduced urine, faintness, confusion, or pain with a single functioning kidney also needs immediate attention. These symptoms matter regardless of whether the collection is complete.

Kidney stones can present with flank pain, abdominal pain, blood in urine, nausea, or painful urination, but these symptoms can have other causes. A test designed for prevention does not replace assessment of an acute attack.

Ask what stone type is suspected, which urine findings are changeable, and how much fluid is suitable for your health. Clarify whether dietary advice applies to salt, animal protein, calcium-containing foods, or another factor. Discuss when to repeat the collection and whether stone analysis, blood work, or imaging would change the plan.