🧪 Lab Values · Lesson 5 of 5 · 5 min
Urinalysis, Specific Gravity and Collecting It Right
🧫 A urine specimen that sat on the counter for two hours grows bacteria that were never in the bladder. The lab reports an infection, the client gets antibiotics, and nobody was sick. Collection technique is a nursing skill the exam tests.
💡 Key idea
Specific gravity 1.005 to 1.030. Nitrites and leukocyte esterase mean infection. Clean-catch midstream, port not bag, lab within an hour, and a 24-hour collection starts with a discarded void.
🧠 Why it matters
URINALYSIS normals: SPECIFIC GRAVITY 1.005 to 1.030, high with dehydration and low with diabetes insipidus or overhydration; pH about 4.5 to 8; protein, glucose, ketones, blood and bilirubin negative; NITRITES and LEUKOCYTE ESTERASE positive in urinary tract infection. Protein in the urine suggests kidney damage or preeclampsia; glucose appears when blood glucose exceeds about 180; ketones appear in diabetic ketoacidosis and starvation. A CLEAN-CATCH midstream specimen requires cleaning the meatus (front to back for a female client), starting the stream, then collecting the middle portion in a sterile container; from a catheter, clamp briefly and draw from the sampling port with sterile technique, never from the bag. Specimens go to the lab within about an hour or are refrigerated. A 24-HOUR URINE collection starts by discarding the first void and noting the time, then saves every void including one at the end time, kept on ice or refrigerated; if a void is missed, the collection restarts. Urine CULTURES are collected before antibiotics. For a STOOL guaiac test, avoid red meat, vitamin C and NSAIDs beforehand; for ova and parasites, deliver warm. SPUTUM cultures are best first thing in the morning, with the client rinsing the mouth with water (not mouthwash), taking deep breaths and coughing from the chest; a swab of saliva is not sputum.
🏥 In the real world
🕐 At 0700 the client voids and the nurse discards it, starting the 24-hour collection. At 1500 an aide empties a void into the toilet by mistake. The nurse starts over: a 24-hour collection with a missing sample is worthless, and reporting it as complete would mislead the provider. The exam asks what to do about the missed void, and the honest answer is restart.
📌 Takeaways
- High specific gravity means concentrated urine and dehydration
- Catheter samples come from the port, never the bag; cultures before antibiotics
- Missed void in a 24-hour collection means restart
📖 Terms in this lesson
Urine specific gravity: How concentrated urine is, normally 1.005 to 1.030; high with dehydration, low with diabetes insipidus.
Urine pH: Normally about 4.5 to 8 (average 6); acidic urine comes with a high-protein diet, acidosis and starvation, alkaline urine with a vegetarian diet, UTI with urea-splitting bacteria, and some kidney stones.
Urine protein: Normally negative on dipstick (under about 150 mg a day); persistent protein means kidney damage, and in pregnancy 300 mg or more in 24 hours, a protein-to-creatinine ratio of 0.3, or a 2+ dipstick helps define preeclampsia.
✅ Test yourself
A client's urine specific gravity is 1.035. Which condition is most consistent with this finding?
- Diabetes insipidus
- Overhydration
- Urinary tract infection
- Fluid volume deficit
Answer: D · Fluid volume deficit
Concentrated urine with a high specific gravity indicates dehydration; diabetes insipidus produces very dilute urine.
A urine culture is needed from a client with an indwelling catheter. Which action is correct?
- Disconnect the catheter from the tubing to collect fresh urine
- Send urine collected over the last 8 hours
- Drain urine from the collection bag into a sterile cup
- Clamp briefly, then aspirate from the sampling port
Answer: D · Clamp briefly, then aspirate from the sampling port
The sampling port, accessed with sterile technique, keeps the system closed and provides fresh urine; bag urine is contaminated and old.
During a 24-hour urine collection, one voided specimen is accidentally discarded. What should the nurse do?
- End the collection early and send what was collected
- Discard the collection and begin again
- Continue the collection and note the missing sample
- Add an estimated volume to the container
Answer: B · Discard the collection and begin again
An incomplete collection invalidates the test; it must be restarted with a new discarded void.
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