Changes in urination: what they may mean

Most people know their own pattern: how often they go, how much they pass, and what their urine usually looks like. When that pattern changes, it is natural to wonder about the kidneys. Some changes are harmless and linked to heat, drinks or age. Others are worth checking. This page explains the common changes and what a clinician may consider.

One important point first: early kidney disease usually causes no change in urination at all. Kidney function is checked with blood and urine tests, not by how urine looks. So a normal pattern does not rule out kidney problems, and a change does not prove one.

Passing more urine than usual

Passing large amounts of urine is called polyuria. Possible reasons include:

• drinking more fluids, tea, coffee or alcohol;
• high blood sugar from diabetes, often with thirst and tiredness. A blood sugar test is a simple first check;
• water tablets (diuretics) or some other medicines;
• some kidney conditions, where the kidneys are less able to concentrate urine.

Getting up at night to pass urine

Waking to pass urine once a night is common, especially with age. Doctors call frequent night-time urination nocturia. It can be linked to drinking late in the evening, an enlarged prostate in men, diabetes, heart conditions, some medicines, poor sleep, or reduced kidney concentrating ability in chronic kidney disease.

Passing less urine

In Mombasa's heat, passing less, darker urine is often a sign of not drinking enough. It usually improves with fluids. But a clear drop in urine output, especially during an illness with vomiting, diarrhoea or fever, can be a sign that the kidneys are under strain. A sudden fall in kidney function is called acute kidney injury, and it needs prompt medical care.

Feeling a need to pass urine but being unable to, with a painful, full lower belly, is called urinary retention. It is often related to the prostate in men and needs urgent care.

Changes in colour or appearance

• Dark yellow or amber: usually concentrated urine from not drinking enough.
• Red, pink or brown: may be blood, but can also be caused by beetroot, some medicines or, rarely, muscle breakdown. Any red or brown urine should be checked.
• Cloudy or strong-smelling: may suggest an infection, though it can also be normal.
• Foamy: often harmless, but persistent foam can be a sign of protein. See foamy urine.

Blood in the urine

Blood that you can see, or blood found on a urine test, is called haematuria. It should always be assessed by a clinician, even if it happens only once and even if there is no pain. Causes a clinician may consider include urinary infection, kidney or bladder stones, an enlarged prostate, inflammation of the kidney filters, and, especially in older adults, growths in the bladder or kidney. In coastal Kenya, clinicians may also think about bilharzia (schistosomiasis), a parasite infection that can cause blood in the urine.

When blood in the urine comes with protein, a raised creatinine or high blood pressure, a clinician may consider kidney causes and may suggest specialist input.

Pain, burning or a weak stream

• Burning or pain on passing urine, needing to go often and urgently: often a urinary tract infection. A fever with pain in the back or side can mean the infection has reached the kidney, which needs prompt care.
• A weak stream, straining or dribbling in men: often related to the prostate.
• Severe pain in the side or back that comes in waves: may be a kidney stone.

Kidney doctor or urinary tract doctor?

A nephrologist deals with how the kidneys work: filtering, protein leak, kidney function and blood pressure related to the kidneys. A urologist is a surgeon who deals with the urinary tract: stones, the prostate, the bladder and blockages. Most people start with a general doctor or clinical officer, who decides which is needed. Read nephrologist vs urologist.

What a clinician usually checks

• Urinalysis, to look for blood, protein, sugar and signs of infection. See urinalysis.
• A urine culture, if infection is suspected.
• Creatinine and eGFR, to estimate kidney function. See kidney function tests.
• Blood sugar, to check for diabetes.
• A kidney and bladder ultrasound, to look for stones, blockage or an enlarged prostate. See kidney ultrasound.

It helps to keep a simple note for a few days before your appointment: how often you go, roughly how much you drink, and any colour changes or pain.

This page explains what a test or condition involves. It is not a diagnosis and does not replace advice from a doctor who knows your history. Your results should be interpreted together with your symptoms, other tests and a clinical assessment. Medical disclaimer.