Akurasi Berat Jenis Urin sebagai Prediktor Gangguan Ginjal Dini pada Pekerja Terpajan Panas: Kajian terhadap Vasopresin, Laju Filtrasi Glomerulus, Albuminuria, Nefrin Urin, dan KIM-1 Urin = Accuracy of Urine Specific Gravity as Predictor of Early Kidney Impairment in Heat-Exposed Workers: Study on Vasopressin, Glomerular Filtration Rate, Albuminuria, Urinary Nephrin and Urinary KIM-1