Help Please log in to determine if you are eligible to purchase PT Programs. KIDNEY STONE RISK ASSESSMENT - KSA Analytes/procedures in bold type are regulated for proficiency testing by the Centers for Medicare & Medicaid Services (CMS). Analyte Challenges per Shipment Number of Shipments Citrate 3 Two shipments per year Cystine 3 Oxalate 3 Sulfate 3 Program Information Three 13.5‑mL liquid urine specimens Shipping Schedule Shipment A: May 24 Shipment B: November 22 Guest Log in/Register