Means for the quantitative determination of cationic electrolyte concentration and creatinine concentration and of their ratios

A single-use test-strip for the quantitative determination of a concentration of a cationic electrolyte which is not sodium, and of creatinine concentration in a patient's urine sample,

• said test-strip comprising:
• a substrate which either is electrically insulating or which has an electrically insulating layer applied thereon,
• an electrode assembly applied on said substrate or on said electrically insulating layer, if present,
• said electrode assembly comprising at least
• one working electrode that is selective for said cationic electrolyte;
• one creatinine-selective working electrode;
• either one joint reference electrode for both said cationic electrolyte-selective working electrode and said creatinine-selective working electrode, or a reference electrode for said cationic electrolyte-selective working electrode and a separate reference electrode for said creatinine-selective working electrode;
• optionally;
• one or two neutral electrodes for measuring and eliminating interferences, and
• an interface for electrically connecting said electrode assembly to a read out-meter device.