Table 3.
Normal values for 24 h urine collection (there should be preservative in the container, either thymol 5% in isopropanol, or 2 N hydrochloric acid (HCL), before collection is started). Repeat collection after stone has been captured, as ongoing stone formation may diminish lithogenic excretion parameters. Check urine volume and creatinine excretion (2 mg/kg ± 0.8 mg) to ensure adequate collection [5, 6, 36–41]
| Parameter age | Normal value per 24 h | Remarks |
|---|---|---|
| Calcium, all ages | <0.1 mmol (<4 mg)/kg | See Table 2 |
| Oxalate | <0.5 mmol (<45 mg)/1.73 m2 | Primary hyperoxaluria types I/II for constant excessive elevation, check also urinary glycolate, L-glycerate and plasma oxalate |
| Secondary hyperoxaluria: determine intestinal oxalate absorption and stool. Oxalobacter formigenes colonization. Normal plasma oxalate different according to laboratory method, but clearly <8 μmol/l | ||
| Citrate | ||
| Male | >1.9 mmol (365 mg)/1.73 m2 | Hypocitraturia: metabolic acidosis, hypokalemia, calcineurin inhibitors |
| Female | >1.6 mmol (310 mg)/1.73 m2 | |
| Uric acid, all ages | <.56 mg/dl per GFR | Hyperuricosuria = > check diet, medication, tumor lysis, inborn errors of metabolism |
| Magnesium | >0.04 mmol (0.8 mg)/kg | FFHNC with hypomagnesemia and elevated FEMg, See Table 2 |
| Phosphate | TmP/GFR | Renal phosphate leakage with low serum phosphate, tumor lysis syndrome with high serum phosphate |
| <3 months | <3.3 mmol/l | |
| <6 months | <2.6 mmol/l | |
| 2–15 years | <2.44 mmol/l | |
| Cystine | ||
| <10 years | <55 μmol (13 mg) /1.73 m2 | Check morning urine for hexagonal crystals |
| >10 years | <200 (48 mg) | |
| Adults | <250(60 mg) | |
| Cystine solubility threshold 160–320 mg cystine/l at ph 5–7 | ||