Protein on the Dipstick with a Normal Albumin-to-Creatinine Ratio
The dipstick measures how concentrated the protein is, so a dehydrated sample reads positive and a dilute one reads negative, both with the same amount of protein leaving your body each day. The ratio corrects for that by measuring protein against creatinine in the same sample. When the two disagree, the ratio is the one to believe.
The pattern on your report
- Urine protein High · mild Key
- Urine ACR Normal Key
- Urine blood Normal Key
- eGFR Normal Supporting
Printed as: eGFR in mL/min/1.73m2Urine ACR in mg/mmolor mg/g— Nearly nine times apart: 3 mg/mmol is about 27 mg/g, and 30 mg/g is the equivalent US threshold.Urine blood in dipstick gradeUrine protein in dipstick grade— Negative, trace or plus signs. It measures concentration and reacts mainly to albumin, so it misses other proteins.
Why the numbers look like this
Urine concentration varies enormously through the day, and everything dissolved in it varies with it. A first morning sample after a night without drinking can be several times more concentrated than one taken in the afternoon, so a fixed amount of protein registers very differently depending on when the pot was filled.
Creatinine is excreted at a steady rate, which makes it a useful yardstick. Dividing protein by creatinine cancels out the concentration and leaves a figure proportional to how much is actually being lost over a day.
The dipstick has a second limitation: it reacts mainly to albumin and detects other proteins poorly, so it can read negative when the protein being lost is a light chain, which is exactly the situation in myeloma.
Not being flagged is not the same as normal
NICE treats a confirmed ACR of 3 mg/mmol or more as clinically important proteinuria, and asks for a second early morning sample to confirm anything between that and 70, while a result of 70 or above needs no repeat. US practice reports the same ratio in mg/g, where the equivalent threshold is around 30. Those two numbers describe the same amount of protein, so a figure quoted in one notation is out by nearly a factor of nine against the other.
What else on the report can hide this
An early morning sample is the standard for confirmation, because it removes both the dilution effect and postural proteinuria, in which protein appears only while upright and disappears overnight. That condition is benign and mostly affects young people, and it is diagnosed precisely by an early morning sample being clean.
Check the other dipstick squares. Blood alongside protein points at the glomerulus and changes the pathway; leukocytes and nitrites suggest infection, which raises urine protein by itself and should be treated before the protein is interpreted.
If myeloma is a consideration, an albumin-specific test is the wrong one. Urine total protein or serum free light chains are what detect light chains, and relying on the ACR is how that diagnosis gets missed.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
A concentrated sample
Dehydration or a first morning sample after a long night. The commonest reason the two tests disagree, and the ratio is unaffected by it.
- Very common
Recent vigorous exercise
Raises urine protein transiently for up to a day or two. A repeat after a rest day resolves it.
- Common
Fever or acute illness
Raises urine protein temporarily. Repeating once well is what separates it from anything persistent.
- Common
Postural (orthostatic) proteinuria — in adolescents and young adults
Protein present during the day and absent overnight. Benign, needs no treatment, and an early morning sample is what identifies it.
- Common
Urinary infection
Raises protein by itself. Leukocytes or nitrites on the same strip, and the protein should be reassessed after treatment.
- Uncommon
A false positive on the strip
Very alkaline urine, contamination with antiseptic, or a strip past its expiry all produce a positive. The ratio does not share these.
- Uncommon
Light chain proteinuria
The reverse problem, and the important one. The dipstick and the ACR both under-detect light chains, so a normal ACR does not exclude myeloma in someone with bone pain, anemia or a raised calcium.
What is usually checked next
- Early morning ACR Removes dilution and postural effects at once, and it is what NICE asks for to confirm a result between 3 and 70 mg/mmol.
- Repeat when well and rested Fever, illness and exercise all raise urine protein, and a repeat separates those from anything ongoing.
- The rest of the dipstick, and a culture if leukocytes or nitrites are present Infection raises protein by itself, and blood alongside protein changes the pathway entirely.
- Urine total protein, or serum free light chains Detects the proteins the albumin-specific test misses. The route by which myeloma is otherwise overlooked.
- Kidney function and blood pressure Puts the finding in context, since albuminuria is staged alongside filtration.
When to seek care sooner
- Same day Frothy urine with swelling of the legs, face or around the eyes
- Same day Blood and protein in the urine together
- Same day A rising creatinine alongside
- Soon Bone pain with a raised calcium or unexplained anemia
- Soon Protein that persists on repeat early morning samples
Questions worth bringing to your appointment
- Was the ACR done on an early morning sample?
- Had I exercised or been unwell before the dipstick was taken?
- Was there blood on the strip as well?
- If myeloma is a possibility, does the ACR miss it?
- Does this need repeating, and how often?