Table 1.
Summary of patient laboratory investigations.
| Parameter | Case 1 | Case 2 | Normal range |
|---|---|---|---|
| Sodium (mmol/l) | 141 | 141 | 135–145 |
| Potassium (mmol/l) | 3.9 | 4.4 | 3.5–5.0 |
| Estimated GFR (ml/min/1.73 m2) | >90 | >90 | >60 |
| Creatinine (umol/l) | 48 | 56 | 50–90 |
| Bicarbonate (mmol/l) | 27 | 25 | 24–32 |
| Haemoglobin (g/l) | 100 | 93 | 120–150 |
| Mean cell volume (f/l) | 78 | 95 | 80–100 |
| ALP (U/l) | 302 | 125 | 30–130 |
| Uric Acid (mmol/l) | 0.21 | 0.35 | 0.25–0.42 |
| Phosphate (mmol/l) | 0.29 | 0.43 | 0.8–1.5 |
| Corrected Calcium (mmol/l) | 2.18 | 2.40 | 2.1–2.6 |
| Magnesium (mmol/l) | 0.84 | 0.83 | 0.70–0.91 |
| Parathyroid hormone (pmol/l) | 4.1 | 8.3 | 1.3–7.6 |
| P1NP (µg/l) | 118 | – | <70 |
| 25(OH) Vitamin D (nmol/l) | 98 | 54 | |
| 1,25(OH) Vitamin D (pmol/l) | 80 | 32 | 60–158 |
| Urinary phosphate (mmol/d) | 8 | 32 | 15–30 |
| Urinary phosphate fractional excretion (%) | 16 | 24 | <5% |
| TmP/GFR | 0.76 | 0.48 | 0.87 – 1.40 |
| FGF23 (pg/ml) | – | 285 | <54 |
| Femoral neck T-score (SD) | –3.0 | –1.3 | >–1.0 |
Parameters in bold indicate an abnormal value.
*
Normal range for fractional excretion of phosphate is 5–20% in patients with normal serum phosphate; a value >5% in the setting of hypophosphataemia is abnormal and denotes isolated renal phosphate wasting.
GFR, glomerular filtration rate; P1NP, procollagen type 1 N propeptide; TmP/GFR, tubular maximum phosphate reabsorption to glomerular filtrate rate; FGF23, fibroblast growth factor 23; SD, standard deviation.