Fasting urine test: what should you know?

A urine sample may be checked for blood, protein, glucose, ketones, white blood cells, bacteria, concentration, or other signs of urinary and kidney problems. Some tests use a clean-catch sample, some require the first urine of the day, and others measure urine collected over a longer period. Food, fluids, medicines, exercise, menstruation, and contamination can affect interpretation. Burning urination, frequency, cloudy or strong-smelling urine, or lower abdominal discomfort can occur with a urinary tract infection, but these symptoms do not establish the diagnosis. Side or back pain with fever can be more concerning for a kidney infection.

Read the container label and instructions before collecting. Wash your hands, clean the genital area as directed, begin urinating into the toilet, then collect the middle part of the stream without touching the inside of the container. Close it firmly and return it within the requested time; ask whether refrigeration is needed if there is a delay. Do not overdrink water to produce a sample, and do not stop antibiotics or other medicines unless the prescriber tells you to. Mention pregnancy, menstruation, urinary devices, or recent treatment because these details can change how the result is read.

Seek urgent assessment for fever with flank or back pain, vomiting, confusion, severe weakness, or feeling acutely unwell. Visible blood in urine, inability to pass urine, or severe pain also needs prompt medical review. A clinician may arrange a urine culture before deciding whether antibiotic treatment is suitable. Persistent weak flow, difficulty starting, or frequent night-time urination should be assessed because benign prostatic hyperplasia and other conditions can affect urinary function.

Do I need to fast, or is a routine sample enough? Which part of the stream should I collect? Should I pause any medicine? How quickly must the sample reach the laboratory, and when will we discuss the result?