At a Glance
This marker is GABA measured in a urine sample, reported as a ratio to creatinine — that is what ug/g Cr means, micrograms of GABA per gram of creatinine. It sits on the HPA profile from Sanesco Health alongside the other neurotransmitters and the adrenal hormones.
Two things first. The range stored here, 600 to 1100 ug/g Cr, is Sanesco's optimal range, not the reference range the laboratory also prints. And a urinary GABA result measures GABA in urine; what it is not is a measurement of GABA in your brain, for reasons set out below that have nothing to do with the quality of the assay.
This is a urine test, not a blood test
Worth stating plainly, because people arrive expecting a blood test: there is no blood GABA number here. The specimen is urine, and the result is expressed per gram of creatinine rather than per volume, correcting for how dilute the sample was.
Creatinine is doing that correcting, and the laboratory is explicit about its role. Sanesco's own report carries the line: "Creatinine is used to calculate results and is not intended to be used diagnostically." The creatinine value on your report is the denominator, not a finding.
How to read your result
Read it against both ranges your report prints, not one.
Sanesco's HPA report gives GABA a reference range of 150 to 700 mcg/g Cr and an optimal range of 600 to 1100 mcg/g Cr. The platform stores the optimal range — and so does the laboratory's own flagging. Sanesco's report carries the legend "(L) & (H) are based on optimal range intervals", so a low or high mark on your paper report is measured against the optimal band too.
That removes a conflict people expect to find. A result of 400 mcg/g Cr sits inside the printed reference range of 150 to 700 and is still marked low — here and on the laboratory's own report, for the same reason. The two overlap only between 600 and 700. So "low" here means "below optimal", which is a different statement from "outside the range the laboratory considers normal". Both ranges are on your report.
mcg/g Cr and ug/g Cr are the same unit written two ways: micrograms per gram of creatinine.
Why another laboratory's GABA range does not apply to this number
This is the practical reason a result on one panel cannot be read against a range from another.
Comparing laboratories takes care, because each one prints two intervals and they are not the same two.
ZRT Laboratory prints a reference interval of 167 to 463 µg/g creatinine with an optimal band of 193 to 367 inside it. Sanesco prints a reference range of 150 to 700 with an optimal band of 600 to 1100. Like against like: ZRT's reference interval falls entirely inside Sanesco's, while the two optimal bands do not overlap at all and sit roughly three-fold apart. Nothing cited here explains why the optimal bands differ, or establishes either as a validated target.
The difference that bites is the flagging rule. Sanesco marks low and high against its optimal band; ZRT marks against its reference interval. So one figure can carry a flag on one report and none on the other, with neither laboratory being inconsistent. A GABA figure read against a range from anywhere else, including another panel in this library, will be misread.
One more reading hazard sits on this very report. Glutamate, which is the molecule GABA is made from, is reported on the HPA panel in mg/g Cr — milligrams — while GABA is in micrograms. Its optimal band is 5 to 10 mg/g Cr. The two are a thousand-fold apart in unit scale, and they invite comparison more than any other pair on the report, because one is the precursor of the other.
What a urinary GABA number can and cannot support
This is the part worth reading slowly, and the honest answer is narrower than either the enthusiastic version or the dismissive one.
The dismissive version says GABA cannot cross the blood-brain barrier, so urinary GABA is meaningless. That is too crude. The primary review in this field calls it "a commonly held misconception that molecules, such as neurotransmitters, cannot be transported from the CNS to the periphery", and describes transporters in the brain's capillary cells that regulate passage outward. A 2025 review calls the GABA evidence conflicting and crossing efficiency "not very high".
The enthusiastic version says the number reflects your brain chemistry. That is not established. The same review concedes the point in its own words: "Although a direct association between neurotransmitters in the CNS and those excreted in the urine is not yet defined." It adds that neurotransmitters are made "in the CNS and most organs in the body", so several systems feed the urinary pool.
There is a specific gap worth knowing about. The validity bibliography offered for urinary neurotransmitter testing — a vendor document, not a systematic review — is built on epinephrine, norepinephrine, serotonin, dopamine and their metabolites. GABA does not appear in it at all. Its serotonin study found cerebrospinal fluid against urine at r=0.62 in eighteen women with fibromyalgia, and serotonin is not GABA.
That is an absence from one bibliography, not an absence from the literature. Urinary GABA has been measured in published human research: a 2026 randomized placebo-controlled trial of a GABA-producing probiotic measured it in a seventeen-person subset, where it rose on the active product and ran inversely to insomnia and anxiety scores at two weeks. The trial was funded by Verb Biotics and included company-affiliated coauthors — the subset is small, and its authors write that peripheral GABA "may only cross the blood brain barrier to a limited extent", proposing a vagus-nerve route instead. It validates neither this panel's optimal band nor any diagnostic cutoff. The honest summary is "barely studied", not "never studied".
What the number is: a real measurement of GABA leaving your body in urine, relative to creatinine. What it is not: a window onto GABA in your brain.
If you remember only one thing
This is a urine measurement, read against the optimal band your laboratory chose, and it does not tell you what GABA is doing in your brain. A flag on it is a flag on a urine ratio — something to take to the clinician who ordered the panel, not something to read a diagnosis or a symptom list off.
Two people, same result
Two people both get 420 ug/g Cr, flagged low.
The first knows what the figure is and what it is not. She can see that 420 is below Sanesco's optimal band and inside its reference range, that the flag follows the optimal band because that is what this laboratory marks against, and that the result describes GABA leaving her body rather than GABA in her brain. She knows her collection details too. She takes it to the clinician who ordered the panel with those questions ready.
The second found the page after searching why she feels anxious, has no clinician involved, and reads the flag as evidence of a GABA deficiency in her brain. The number cannot support that, and nothing else on the report can either.
The figure is identical. What separates them is that the first is asking the number a question it can answer. A clinician helps by weighing the result against your history, medications and collection conditions — not because reading more markers at once turns an unvalidated measurement into a validated one.
What this result cannot tell you
Your brain's GABA level or activity. The association between what is in the central nervous system and what is excreted in urine is, in the primary review's words, not yet defined.
Whether your symptoms are caused by GABA. There is no validated mapping from a urinary GABA figure to anxiety, sleep difficulty or any other symptom, and this page does not offer one.
Whether a supplement is warranted or working. Nothing cited here establishes that this number should start, stop or titrate anything.
Where the GABA came from. Multiple organs make it, gut bacteria make it and food contains it, so the urinary pool has several contributors this number does not separate.
And it cannot be compared against a range from a different laboratory: ZRT's optimal band for the same analyte in the same units is 193 to 367 µg/g creatinine against this panel's 600 to 1100, and the two laboratories do not even flag against the same interval.
Common interpretation mistakes
Reading it as a brain measurement. It is a urine ratio.
Reading "low" as outside the laboratory's reference range. It means below the optimal band, which starts 450 units higher — and that is how the laboratory's own report marks it too.
Comparing the number to a range found elsewhere. ZRT's optimal band is roughly a third of this one, and ZRT flags against its reference interval instead.
Comparing GABA directly to glutamate on the same report without checking the units. One is in micrograms per gram creatinine, the other in milligrams.
Treating the creatinine line as a result. The laboratory states it is used to calculate results and is not intended to be used diagnostically.
Reading a symptom list off the number. No such mapping is established for urinary GABA.
Questions your doctor may ask
What were you hoping this panel would explain, and who ordered it? When was the sample collected relative to waking, and had you been fasting? Are you taking GABA or any supplement marketed for calm or sleep, and for how long? Any medication acting on GABA pathways — a benzodiazepine, gabapentin, pregabalin? Any kidney problem, since the result is relative to creatinine? And what would change in your care depending on the answer, which is what decides whether this number is worth acting on at all.
Read together with
This number means little alone, though no published source here establishes that the pattern across the panel carries a meaning its individual lines do not. Reading several unvalidated markers together does not add up to a validated one.
Glutamate is the obvious one to set beside it: GABA is synthesized from it, both sit on this report, and both are reported relative to creatinine — in different units. A precursor relationship in biochemistry is not evidence that two urine ratios measure a balance between excitation and inhibition. Serotonin is the other inhibitory marker on the panel. Dopamine, norepinephrine, epinephrine, PEA and the norepinephrine-to-epinephrine ratio make up the excitatory side.
The adrenal half of the profile is the four cortisol timepoints and the two DHEA-S measurements, which is where the hypothalamic-pituitary-adrenal part of the panel's name comes from.
Creatinine is on the report because every other urinary value here is expressed against it.
Clinical pearls
A ratio is not a concentration. Everything on the urinary half of this panel is normalized to creatinine, which means the denominator can move the number without anything changing in the numerator.
An optimal range and a reference range are two different intervals, and this record stores the optimal one — which is also the one Sanesco flags against, per the legend on its own report. "Optimal" is the laboratory's label for a second, narrower band; the sources cited here do not establish it as a validated treatment target.
Optimal bands for urinary GABA are laboratory-specific to an unusual degree — ZRT's 193 to 367 µg/g creatinine against this panel's 600 to 1100, no overlap, while ZRT's reference interval sits entirely inside Sanesco's. The two laboratories also flag against different intervals.
Clinical Takeaway
This is GABA in urine, per gram of creatinine, on Sanesco's HPA profile. The stored range of 600 to 1100 ug/g Cr is the laboratory's optimal band rather than its reference range of 150 to 700, and it is the interval Sanesco flags against on its own report, so a result between 150 and 600 reads as low in both places. Another laboratory's range does not transfer: ZRT's optimal band is 193 to 367 for the same analyte and units, and ZRT flags against its reference interval instead. On meaning: this measures GABA leaving the body in urine. It is not established as a measure of brain GABA — the primary review calls the CNS-to-urine association "not yet defined", the vendor bibliography cited here does not mention GABA, and the one randomized trial to measure it was small, industry-funded and made no brain-level claim. Read it with the clinician who ordered it, and do not read a diagnosis or a symptom list off it.
In one sentence
A real measurement of GABA in urine, read against one laboratory's optimal band, and not a window onto GABA in the brain.
Bottom line
If this line is flagged, take the whole report to whoever ordered it rather than acting on the single number — and if nobody ordered it, that conversation is the thing worth arranging before anything else.
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Frequently Asked Questions
Is this a blood test for GABA levels?
Does urinary GABA tell me my brain GABA level?
Why does my result say low when it is inside the range on my report?
Can I compare my number to a GABA range I found somewhere else?
What does ug/g Cr mean?
Can a urinary GABA result explain my anxiety or sleep problems?
Should I take a GABA supplement based on this result?
What else on the HPA report should I look at alongside this?
Is there a better way to measure GABA activity in the brain?
All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.
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LOINC 28593-2 — Gamma aminobutyrate/Creatinine [Ratio] in Urine
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NeuroLab HPA Profile (Hypothalamic-Pituitary-Adrenal Axis) — sample report
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Marc DT, Ailts JW, Campeau DC, Bull MJ, Olson KL. Neurotransmitters excreted in the urine as biomarkers of nervous system activity: validity and clinical applicability. Neurosci Biobehav Rev. 2011;35(3):635-644
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Jiang C, Chen Y, Sun T. From the gut to the brain, mechanisms and clinical applications of gamma-aminobutyric acid (GABA) on the treatment of anxiety and insomnia. Front Neurosci. 2025;19:1570173
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Validity of Neurotransmitter Testing — bibliography
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Audhya T, et al. Correlation of serotonin levels in CSF, platelets, plasma and urine. Biochim Biophys Acta. 2012;1820(10):1496-1501
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GABA — ZRT Laboratory (Urinary Neurotransmitters), stored interval
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Glutamate — HPA (NeuroLab), stored interval
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Grant AD, Erfe MCB, Delebecque CJ, et al. Lactiplantibacillus plantarum Lp815 improves sleep and increases urinary GABA in a randomized, double-blind, placebo-controlled study of sleep disturbance. Sci Rep. 2026;16:644
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Alammary D, Low T, Srinivasan G, et al. Identification of Additional Cases of Severe Neonatal GABA-Transaminase Deficiency. JIMD Rep. 2026;67(1):e70069
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Neurotransmitters, Urine — ZRT Laboratory sample test report