GPT and metabolic dysfunction-associated steatotic liver disease: In a Korean study, 3878 adolescents (including 78.9% with suspected NAFLD, defined as an increased alanine transaminase concentration >30 U/L) presented hypovitaminosis D (25-hydroxyvitamin D levels < 20 ng/mL); therefore, adolescents with vitamin D deficiency were considered at increased risk of NAFLD [138].