Approach to hypophosphatemia atee new

• 1. Dr Nur Karyatee binti Kassim Mpath 4th year Approach to Hypophosphatemic patients

2. Case History 65 y.o man , developed right medial knee pain while golfing. A tibial stress fracture was identified. He then developed a contralateral stress fracture and generalized pain and weakness in his legs and back. He had no previous history of fracture or childhood rickets. 3. Case History Past Medical History: Type 2 diabetes, hypercholesterolemia and hypertension Drug History : Glipizide, quinapril, and atorvastatin. Tab calcium (1000mg) and vitamin D 600 units daily acetaminophen, rofecoxib, and tramadol (pain) Family history was unremarkable. 4. On examination Hypertensive (147/81mmHg) wt : 99.2 kg , Ht : 182 cm. Normal dentition, without intraoral masses. No palpable masses in his neck or extremities. Examination of lungs, heart, and abdomen was normal. He required a walker to ambulate, used his arms to rise from a chair, but could do a sit-up. 5. Laboratory testing Se Phos :ranging fr 0.35 to 0.55 mmol/L () Se Calcium : 2.22 mmol/L (N) Se PTH : 4.95 pmol/L (N) Se Creatinine : 71 mmol/L (N) 25-hydroxyvitamin D (25OHD) : 65 nmol/l (N) 1,25-dihydroxyvitamin D (1,25OHD) : 60 pmol/l (N) ALP : 66 171 U/liter () FGF23:97 pg/ml ( N: 20% renal cause 30. Tmp/GFR Determine renal /non renal causes Assessment of TmP/GFR Tubular reabsorption of phosphate (TRP) is calculated using the formula: 1- (urine phosphate x serum creatinine) (serum phosphate x urine creatinine) TmP/GFR (normal range) = same numerical range as the age appropriate serum phosphate concentration in mg/dL 31. Normogram for determining TmP/GFR 32. Tmp/GFR If both serum phosphate and TmP/GFR : inappropriate renal phosphate wasting Normal se PO4 / TmP/GFR renal conservation of phosphate (non renal hypophosphatemia) 33. Laboratory assessment 8.) FGF23 measurement : not yet routinely available. Potentially useful in evaluating chronic hypophosphatemia 34. DDX PO4 Ca PTH ALP 1,25(O H)D FGF 23 TMP/G FR U Ca FGF23 MEDIATED XLH,ADHR,ARH R,TIO,FD,post renal transplant N /N /N Non-FGF23 MEDIATED HHRH( NPT2C) N /N Pry PTH /N N/ N/ Diuretics N/ N N N N Fanconi syndrome N/ N/ N/ N/ Summary 35. Non Renal Hypophospha temia PO4 Ca PTH ALP 1,25(O H)D FGF 23 TMP/G FR U Ca Impaired intestinal Absorption /intake N/ N/ /N Phosphate binders N/ N/ N/ Intracellular uptake N /N Refeeding syndrome N N N /N/ Summary 36. Back to the patient TmP/GFR renal phosphate wasting No aminoaciduria PTH : 4.95 pmol/L (N) Dual-energy-xray absorptiometry T score - 2.2signifies osteopenia FGF23 : 97pg/ml ( normal