In turn, the study of patients with early (eGFR >  60 mL/min/1.73 m2) and advanced stages of CKD (< 30 mL/min/1.73 m2) on LPD demonstrated that this diet reduced intact FGF23 levels in both groups, while the decrease in serum phosphorus and PTH was seen only in advanced CKD [99]. The gene discussed is FGF23; the disease is chronic kidney disease.