低钠血症常见于（） ["大量出汗","糖尿病性多尿","垂体肿瘤","肾上腺皮质功能亢进症","尿崩症"] 低钠血症是指血清钠低于（） ["135mmol/L","145mmol/L","155mmol/L","165mmol/L","175mmol/L"] 高钠血症是指血清钠超过（） ["135mmol/L","145mmol/L","155mmol/L","165mmol/L","175mmol/L"] 轻度低钾血症是指血清钾为（） ["2.5mmol/L","2.5～3.0mmol/L","3.0～3.5mmol/L","3.5～4.0mmol/L","4.0～4.5mmol/L"] 低钾血症是指血清钾低于（） ["2.5mmol/L","3.5mmol/L","4.5mmol/L","5.5mmol/L","6.5mmol/L"] 细胞外液的主要阳离子是（）