What does the Krebs Cycle (TCA Cycle) Organic Acid Markers test measure?

Why is Krebs Cycle (TCA Cycle) Organic Acid Markers measured?

Elevation of specific TCA intermediates provides evidence of mitochondrial metabolic dysfunction at identifiable enzymatic steps. Elevated succinic acid suggests succinate dehydrogenase impairment — relevant in SDH-related paraganglioma/phaeochromocytoma and mitochondrial complex II deficiency. Elevated alpha-ketoglutaric acid with pyruvic acid suggests pyruvate dehydrogenase or alpha-ketoglutarate dehydrogenase dysfunction — associated with thiamine deficiency, lipoic acid deficiency, or mitochondrial disease. In functional and integrative medicine, mild TCA intermediate elevations are interpreted as evidence of mitochondrial metabolic stress — guiding nutritional cofactor support (B vitamins, alpha-lipoic acid, CoQ10, carnitine) in patients with fatigue, cognitive impairment, and reduced exercise tolerance.

Reference ranges

Standard reference

# REVIEWER FLAG: Confirm Mosaic Diagnostics reference ranges for individual Krebs cycle metabolites — citric acid, isocitric acid, cis-aconitic acid, succinic acid, fumaric acid, malic acid, alpha-ketoglutaric acid, and oxaloacetic acid. Each has a distinct creatinine-corrected reference interval proprietary to Mosaic Diagnostics' population dataset.

Functional medicine optimal

# REVIEWER FLAG: Confirm Mosaic Diagnostics' interpretive zones for TCA markers — optimal (within reference range), borderline, and elevated tiers as documented in the Mosaic OAT interpretive guide.

Units

mmol/mol creatinine

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.