Makindo Medical Notes

💉 IV phosphate if serum PO₄ < 0.32 mmol/L or severe symptoms. 🍽️ Low phosphate can trigger refeeding syndrome.

📏 About

• ✅ Normal range: 0.8 – 1.4 mmol/L
• 🚨 Severe: < 0.4 mmol/L (1.24 mg/dL)

🧬 Aetiology

• 🏥 Phosphate reabsorption in renal PCT
• 📉 Decreased uptake with PTH

🩺 Causes

🧾 Cause	🤒 Clinical Features	🔬 Investigations	💊 Management
🍽️ Refeeding Syndrome	Weakness, respiratory failure, arrhythmias, confusion after feeding malnourished patient	Check PO₄, Ca²⁺, K⁺, Mg²⁺; monitor during refeeding	Slow nutrition, PO/IV phosphate, close monitoring
🍷 Chronic Alcoholism	Weakness, tremor, seizures; often with low Mg²⁺ & K⁺	Serum PO₄, Mg²⁺, K⁺; LFTs, renal function	PO/IV phosphate, nutrition, treat alcohol dependence
💉 Diabetic Ketoacidosis (DKA)	Occurs during insulin therapy: weakness, confusion	Glucose, ketones, PO₄, blood gases, K⁺, Mg²⁺	IV fluids, insulin, phosphate if very low
🦴 Hyperparathyroidism	Bone pain, stones, weakness; hypercalcaemia features	Ca²⁺, PO₄, PTH, urine phosphate	Treat underlying cause ± phosphate support
🥀 Malnutrition	Fatigue, weakness, bone pain, infection risk	Serum PO₄, Ca²⁺, Mg²⁺, albumin; nutrition review	PO/IV phosphate, nutritional support
🧪 Renal Tubular Disorders (e.g., Fanconi)	Polyuria, rickets/osteomalacia, growth delay	PO₄, Ca²⁺, bicarbonate, K⁺; urine glucose, amino acids	PO phosphate, bicarbonate & K⁺ supplements, treat cause
💊 Medications (antacids, diuretics)	Weakness, bone pain, low phosphate symptoms	Check PO₄, Ca²⁺, Mg²⁺; review meds	Stop offending drug, PO phosphate, correct electrolytes
🌬️ Respiratory Alkalosis	Cramps, tetany, confusion from hyperventilation	ABG, PO₄, Ca²⁺, K⁺	Treat cause of hyperventilation, phosphate if severe

🧠 Clinical Features

• Asymptomatic → muscle weakness, myalgia, rhabdomyolysis
• Seizures, delirium, tremor, paraesthesia
• Respiratory failure (weak diaphragm)
• Cardiac failure (myocardial weakness)
• Osteomalacia, haemolysis, coma

🔗 Associations

• Osteomalacia, bone pain, insulin resistance
• Glycosuria, hypercalciuria, hypermagnesaemia

🔬 Investigations

• U&E, Creatinine
• Ca²⁺, Mg²⁺, PO₄, ALP, VBG

💊 Management

• Mild (0.6–0.69 mmol/L)
  • Usually outpatient: manage cause, diet rich in phosphate
  • Oral replacement (e.g. Phosphate Sandoz)
• Moderate (0.4–0.59 mmol/L)
  • Replace if symptomatic or high risk
  • Phosphate Sandoz 1–2 tablets PO TDS
  • If severe symptoms → IV phosphate (e.g. 25 mmol over 12h)
• Severe (<0.4 mmol/L)
  • IV phosphate (e.g. 100 mmol in 500 mL over 8–12h)
  • ⚠️ Avoid if hypercalcaemic or oliguric

⚠️ Cautions

• Rapid phosphate infusion → hypocalcaemia, calcification
• Renally cleared → use with caution in CKD

📚 References

• GGC Medicines: Management of Hypophosphataemia
• SPS: Acute Hypophosphataemia