SIADH：V=1，U_osm=600，P_osm=260 → C_H2O = −1.308 mL/min（浓缩尿） C_H₂O = 1·(1 − 600/260) = −1.308 mL/min。负值→浓缩尿保留游离水，符合 SIADH。此处未提供电解质游离水清除率。{"result":"C_H₂O = −1.308 (Negative — concentrated urine). C_H₂O = V·(1 − U_osm/P_osm).","metadata":{"input":{"urineFlow":1,"urineOsm":600,"plasmaOsm":260},"result":{"osmolarClearance":2.3077,"freeWaterClearance":-1.3077,"category":"Negative — concentrated urine","interpretation":"C_H₂O < 0 (U_osm > P_osm): kidney conserves free water. Seen with hypovolemia/dehydration (appropriate ADH) or SIADH (inappropriate ADH with inappropriately concentrated urine despite low plasma osmolality).","method":"C_H₂O = V·(1 − U_osm/P_osm); C_osm = U_osm·V/P_osm","model":"Rose BD; Shimizu 2002 Nephron; NephSIM. Not medical advice."}}}
尿崩症/多饮：V=5，U_osm=80，P_osm=290，U_Na=20，U_K=10，P_Na=125 → eC_H2O = +3.8（稀释） C_H₂O = 5·(1 − 80/290) = +3.621 mL/min；电解质游离水清除率 eC_H₂O = 5·(1 − (20+10)/125) = +3.800 mL/min。正值→稀释尿排出游离水（尿崩症/多饮）；eC_H₂O 正值也提示尿液相对富含电解质，排出后使血钠下降。{"result":"C_H₂O = 3.6207 (Positive — dilute urine). eC_H₂O = 3.8. C_H₂O = V·(1 − U_osm/P_osm).","metadata":{"input":{"urineFlow":5,"urineOsm":80,"plasmaOsm":290,"urineSodium":20,"urinePotassium":10,"serumSodium":125},"result":{"osmolarClearance":1.3793,"freeWaterClearance":3.6207,"category":"Positive — dilute urine","interpretation":"C_H₂O > 0 (U_osm < P_osm): kidney excretes solute-free water. Seen with central/nephrogenic diabetes insipidus, primary polydipsia, or the recovery/diuretic phase after water load. Tends to raise serum Na⁺ unless water intake is sufficient.","electrolyteFreeWaterClearance":3.8,"electrolyteFreeCategory":"Positive — electrolyte-free water excretion (tends to LOWER serum Na)","electrolyteFreeInterpretation":"eC_H₂O > 0: urine is electrolyte-rich relative to plasma, so excreting it removes water and electrolytes proportionally → tends to lower serum Na⁺ (or fail to correct it).","method":"C_H₂O = V·(1 − U_osm/P_osm); eC_H₂O = V·(1 − (U_Na+U_K)/P_Na)","model":"Rose BD; Shimizu 2002 Nephron; NephSIM. Not medical advice."}}}