While several hormones influence phosphate balance, Fibroblast Growth Factor 23 (FGF23) has emerged as the primary hormone regulating phosphate homeostasis. It is produced by osteocytes and osteoblasts in bone. FGF23 acts on the kidneys to: 1) Increase phosphate excretion by suppressing the expression of sodium-phosphate cotransporters in the proximal tubule, promoting phosphaturia. 2) Inhibit the enzyme 1α-hydroxylase, reducing the production of active vitamin D (calcitriol), which in turn decreases intestinal phosphate absorption. Parathyroid hormone (PTH) also promotes phosphaturia but has opposing effects on vitamin D (it stimulates 1α-hydroxylase). FGF23 works in concert with PTH and vitamin D to maintain normal serum phosphate levels. Dysregulation of FGF23 is involved in disorders like familial hypophosphatemic rickets and chronic kidney disease-mineral bone disorder (CKD-MBD).

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Zambia

• Joseph Soko – 101 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies