Hypophosphataemia occurs in an abnormally low serum phosphate level. Three main mechanisms are postulated: decreased intestinal absorption, increased renal excretion, and extracellular shifts to intracellular compartments. It is potentially a fatal disease if not intervene. The management is merely treating the underlying disorder, giving phosphate supplement and requiring close biochemical monitoring. The incidence of symptomatic isolated hypophosphataemia is extremely rare. In this case report, a 33-year-old man presented with three days history of dysphagia, inability to complete sentences and generalized muscle weakness. He developed blurred vision especially upon exposure to bright light. He had a history of single parathyroidectomy for parathyroid adenoma 2 years ago. Physical examinations were unremarkable. Laboratory investigations were normal except for phosphate level of 0.30 mmol/L. Intravenous KH2PO4 with a dosage of 10 mmol was administered in slow bolus in 3 hours. His symptoms resolved slowly after correction. Although isolated hypophosphataemia is rare but need to recognize the symptoms and signs of hypophosphataemia and treat accordingly.
Hypophosphatemic osteomalacia is a rare form of metabolic bone disorder in neurofibromatosis type 1 (NF1). The exact disease mechanism of this disorder in NF1 is yet to be established. We present a 44-year-old female known to have NF1, who presents with debilitating bone pain, weakness and multiple fractures. Laboratory investigations showed persistent hypophosphatemia with renal phosphate wasting suggestive of hypophosphatemic osteomalacia. She also had concomitant vitamin D deficiency which contributed to the disease severity. Medical therapy with oral phosphate and vitamin D improved her symptoms without significant changes in fracture healing or phosphate levels.