Alanine-aminotransferase: an early marker for insulin resistance? / Alanino-aminotransferasa: un marcador temprano de resistencia a la insulina?

ABSTRACT

In a population-based sample, after excluding alcohol consumption, hepatotoxic drugs and hepatitis Band C infected, we investigated if alanine-aminotransferase (ALT) was associated with metabolic syndrome and insulin resistance, and if this association was caused by non-alcoholic fatty liver disease (NAFLD). The sample (432 female and 119 male) was divided into two ALT thresholds corresponding to the 50th and 75th percentiles (P) (female < or = 15 and < or = 19 U/L; male < or = 17 and < or = 23 U/l, respectively). Blood pressure, body mass index, waist circumference, cholesterol, HDL cholesterol (HDLc), triglyceride (TG), TG/HDLc ratio, glycemia and homeostasis model assessment of insulin resistance (HOMA-IR) were compared between those above and below each ALT threshold. Female placed above the 50th P of ALT had higher levels of TG/HDLc ratio (p=0.029), glycemia (p=0.028), and homeostasis model assessment of insulin resistance, (p=0.045), and above the 75th P had higher SBP (p=0.036), DBP (p=0.018), TG (p=0.024), TG/HDLc ratio (p=0.028), glycemia (p=0.004) and HOMA-IR (p=0.0014). Male placed above the 50th P of ALT had higher BMI (p=0.017) and TG/HDLc ratio (p=0.048), and above the 75th P had lower values of HDLc (p=0.042). Only 16.5 percent of women and 14.5 percent of men, above the 75th P of ALT, showed an increase in liver brightness in the echography. This work shows in woman an early association of ALT with TG/HDLc ratio and HOMA-IR. Since the last two are independent predictors of cardiovascular risk, attention should be drawn to ALT values near the upper limit of the normal range even in the absence of NAFLD and obesity.

RESUMEN

En una muestra poblacional, luego de excluir a quienes consumían alcohol y drogas hepatotóxicas y a los infectados con virus B y C de la hepatitis, investigamos si la alanino-aminotransferasa (ALT), o transaminasa glutámico pirúvica (TGP), se asociaba con el síndrome metabólico y con resistencia a la insulina y si esta asociación se explicaba por enfermedad hepática grasa no alcohólica (NAFLD). La muestra (432 mujeres y 119 varones) se dividió por los percentilos (P) 50 y 75 de la distribución de ALT (mujeres < o = 15 y < o = 19 U/l; varones < o = 17 y < o = 23 U/l, respectivamente). Las mujeres a partir del P50 de ALT tuvieron valores más altos de índice triglicéridos (TG)/HDLc (p=0.029), glucemia (p=0.028) y de la valoración del modelo homeostático de insulino-resistencia (HOMA-IR) (p=0.045); a partir del P75 tuvieron valores más altos de presión arterial sistólica (PAS) (p=0.036), presión arterial diastólica (PAD) (p=0.018), TG (p=0.024), índice TG/HDLc (p=0.028), glucemia (p=0.004) y HOMA-IR (p=0.001). Los varones a partir del P50 de ALT tuvieron valores más altos del índice de masa corporal (p=0.017) y del índice (TG/HDLc (p=0.048); a partir del P75 mostraron valores más bajos de HDLc (p=0,042). Sólo 16.5 porciento de las mujeres y 14.5 porciento de los varones, a partir del P75 de ALT, mostraron aumento del brillo hepático en la ecografía. Este trabajo muestra, en mujeres, asociación temprana de ALT con el índice TG/HDLc y el HOMA-IR. Dado que estos dos últimos son predictores independientes del riesgo cardiovascular se debería prestar atención a los valores de ALT cercanos al límite superior aun en ausencia de NAFLD y de obesidad.