Does GGT tell me anything about hepatic fat on oral semaglutide?

Conditions: GGT · oral semaglutide.

I want to know whether this is a real physical effect or an artefact of how it is measured.

What prompted the question is an inconsistency between two sources I otherwise trust.

Why does this happen, and what would falsify the usual explanation?

Before attributing anything to a compound, account for alcohol, muscle injury from new training, and any over-the-counter product being taken alongside.

Hy's law describes the combination that matters: transaminases above three times the upper limit together with bilirubin above twice the upper limit and no cholestatic explanation. That combination is a signal; isolated mild transaminase elevation is not.

Weight loss of ten per cent or more typically reduces transaminases substantially in people whose elevation was driven by hepatic fat, which is the majority of mild elevations in this population.

Trials in this class have generally reported improvement rather than deterioration in liver biochemistry, consistent with the weight-mediated mechanism.

Read the pattern before the magnitude, and the magnitude in multiples of the upper limit.

Answering this needs the magnitude in multiples of the upper reference limit, because the thresholds that matter clinically are defined that way and not in absolute units.

Creatine kinase, alkaline phosphatase and bilirubin together tell you which compartment the abnormality is in, and ordering the transaminases alone throws that information away.

Reference upper limits around forty units per litre for ALT are conventional rather than physiological; several groups have argued for limits closer to thirty for men and twenty-five for women.

Hy's law and its variants are the standard framework for identifying drug-induced liver injury in trials and are why bilirubin is measured alongside transaminases rather than instead.

Attributing an enzyme change to a compound requires a baseline, and most people asking have not got one.

Get a baseline before you start anything, because it converts an uninterpretable result into an interpretable one for the cost of one blood draw.

Answer first: mild transaminase elevation is common in this population before any drug is involved, and the usual cause is hepatic steatosis rather than anything acute.

Gamma-glutamyl transferase is sensitive and unspecific: it rises with alcohol, with several medications and with fatty liver, and an isolated elevation rarely changes anything on its own.

An isolated result three weeks after starting anything is difficult to interpret. A baseline taken before starting makes the same result trivially interpretable, which is the argument for baselines.

Research-use material of unknown content is an unquantifiable variable in any such attribution.

New training, alcohol and over-the-counter products first. Then the interesting hypotheses.

edited 23 Aug 2024 by kofi_mensah — expanded the table to cover the lower concentration

The short version: enzymes in this class usually fall as weight falls, and a rise is a reason to look for a cause rather than to assume a drug effect.

Alanine aminotransferase is relatively liver-specific; aspartate aminotransferase is also present in muscle, heart and red cells. A raised AST with a normal ALT after heavy resistance training is usually muscle, and creatine kinase settles the question.

Laboratory-specific reference intervals for transaminases vary enough that cross-laboratory comparison of borderline values is unreliable.

Nothing here is medical advice. An abnormal result needs somebody who can take a history and examine you.

Isolated mild elevation is common and usually improves with weight loss.

The relevant caution is that a rapid rise, particularly with bilirubin, is a different event from a stable mild elevation and needs handling differently.

Very rapid weight loss can transiently worsen liver biochemistry, which is one of several arguments against pursuing the steepest possible trajectory.

The caveat is direct: rising liver enzymes with jaundice, dark urine or right-upper-quadrant pain is a same-day clinical problem, not a forum question.

Transaminases plus bilirubin plus alkaline phosphatase, or you have not measured enough to conclude anything.