1st order laboratory parameters – obligatory laboratory tests.
- Small blood count
- Inflammatory parameters – CRP (C-reactive protein).
- Urine status (rapid test for: Nitrite, protein, hemoglobin, erythrocytes, leukocytes, urobilinogen) incl. sediment, if necessary urine culture (pathogen detection and resistogram, that is, testing of suitable antibiotics for sensitivity / resistance).
- Electrolytes – calcium, sodium, potassium, phosphate.
- Renal parameters – urea, creatinine, cystatin C or creatinine clearance, if necessary.
- Alpha-1 microglobulin in urine – to exclude tubular proteinuria.
2nd order laboratory parameters – depending on the results of the history, physical examination and obligatory laboratory parameters – for differential diagnostic clarification.
- Genetic diagnostics (usually not indicated because, for example, autosomal dominant polycystic kidney disease (ADPKD) can usually be clearly diagnosed with ultrasound)
Further notes
- Note: Many patients with cystic kidneys often do not develop albuminuria (increased albumin concentration in urine)/proteinuria (increased excretion of protein in urine) at all, often not even until end-stage renal disease is reached!
- A new renal marker, profibrotic glycoprotein Dickkopf 3 (DKK3), secreted by renal tubule cells under stress conditions, is detectable in patients with cystic kidneys. A strong correlation between urinary DKK3 concentration and the expression of tubulointerstitial fibrosis has been demonstrated.Material needed: 1 ml spontaneous urine (frozen at -20 °C or refrigerated at 4 °C if measurement is performed within 24 hours); Method: ELISA testNew data from the Homburg research group presented at the European Kidney Congress (ERA-EDTA Congress 2018) in Copenhagen showed that DKK3 can also be used as a marker of CKD progression:
- Median DKK3/creatinine ratio was significantly higher in CKD patients than in the general population (431 vs. 33 pg/mg creatinine), independent of eGFR (estimated GFR, the estimated glomerular filtration rate) and albuminuria (increased albumin concentration in urine)
- Urinary DKK3 concentrations correlated significantly with CKD progression (progression of chronic kidney disease)
- DKK3 concentration > 1,000 pg/mg creatinine was associated with a mean annual GFR loss of 2.4% (p=0.007)
- DKK3 concentration > 4,000 pg/mg creatinine was associated with a 7.6% loss (p < 0.001),