Water and electrolyte disorders

一、水、电解质代谢的生理基础 (一) 体液 1. 体液及其分布 Intracellular fluid Total (ICF) 40% (60%) interstitial fluid 15% extracellular fluid plasma 5% (ECF) 20% transcellular fluid 2% (透细胞液)

在Na+- K+-ATPase作用下，细胞内外Na+ 、K+保持不对等分布。 2. 体液中主要电解质及其分布 extracellular fluid: Na+、Cl-、HCO3- intracellular fluid： K+、HPO42- 在Na+- K+-ATPase作用下，细胞内外Na+ 、K+保持不对等分布。

3. Osmotic pressure of body fluid (plasma) Positive ion: 151mmol/L Negative ion: 139mmol/L total 280-310mmol/L Nonelectrolyte: 10mmol/L (678.3kpa) Plasma colloidal osmotic pressure: 3.72kpa(28mmHg)

（二） movement of water and electrolytes 1. plasma interstitial fluid capillary protein   2. intra- and extra- cellular fluid proteins and positive ion: permeability water and negative ion: permeability (water movement balance of osmotic pressure) R B C

3. Balance of body water and sodium drink 1200ml water intake food 1000ml (2000-2500ml) oxidation 300ml  balance of water urine 1200-1500ml water loss skin 500ml (2000-2500ml) respiration 350ml feces 150ml   Balance Intake/d 100-200mmol (digestive tract) of sodium Loss/d 100-200mmol (urinary system) ECF:50% Distribution ICF: 10% of sodium 骨基质:40% (正常血清钠:130-150mmol)

(三) Regulation of osmotic pressure and volume Hypertonic thirst of ECF 1.body water ADH ; aldosterone sodium thirst Ang Ⅱ ADH body volume aldosterone receptor of volume ADH   2.body water sodium ADH reabsorption of sodium 3.blood volume ANP aldosterone(ADS) tension 4.others ADH pain

Figure: regulation of ADH secretion osmotic pressure R volume R heart

二、water and sodium disorders hypertonic hypertonic dehydration isotonic water excess isotonic hypotonic hypotonic (一) 细胞外液容量不足(extracellular fluid deficit) 1. Hypotonic dehydration sodium loss ＞ water loss serum sodium ＜ 130mmol/L plasma osmotic pressure ＜ 280mOsm/L

1) cause and Pathogenesis excessive loss of water and sodium replaced with water only. vomiting, diarrhea; burn; diuretics; Addison’s disease (ADS ) ; chronic renal failure; renal tubular acidosis 2) adaptive response and effect on body ①  movement of body fluid ECF ICF cellular swelling Blood volume Extracellular fluid   Shock dehydrated signs edema of brain and lung

 ②  urinary alteration urine specific urine volume gravity [Na+] ---------------------------------------------------------- early ADH ± or stage ADS   late ADH stage ADS ----------------------------------------------------------- (注：经肾失钠的低渗性脱水，尿钠不减少)

3) principles of treatment ①  treating primary disease ②  0.9%NaCl 2. hypertonic dehydration ① water loss ＞ sodium loss ② serum sodium ＞ 150mmol/L ③ plasma osmotic pressure＞310mOsm/L

1) cause and pathogenesis lack of water(desert;sea) ①  intake to drink inability(coma;baby) lung: hyperpnea(hypoxia;acidosis)  skin: fever; hyperthyroidism; sweat; exposure to hot environment  ②  loss digestive tract: vomiting; diarrhea; baby diarrhea([Na+]: 60mmol/L) kidney: diabetes(ketosis); diabetes insipidus diuretic(mannitol;hypertonic glucose)

2) effect on body ①   hypertonic of ECF thirst ②   movement of the body fluid ICF ECF cell dehydration   Brain dehydration Sleepiness subarachnoid space bleeding Dehydration of sweat glands dehydrated fever dehydration of heat regulating center

③urinary alteration urine specific urine volume gravity [Na+] ---------------------------------------------------------------- early ADH stage ADS ±   late ADH stage ADS  ----------------------------------------------------------------- 3) principles of treatment 先水，后盐；补水大于补钠。

病例1：患者，男性，40岁，吐、泻伴发热、口渴、尿少4天入院。 体格检查：体温 38.2℃，血压 110/80mmHg，汗少，皮肤黏膜干燥。 实验室检查：血Na+ 155mmol/L，血浆渗透压320mOsm/L，尿比重﹥1.020。 给予 5%葡萄糖溶液 2500ml/d 和抗生素，2天后体温、尿量正常，口不渴，眼窝凹陷，皮肤弹性明显降低，无力，肠鸣音减弱，腹壁反射消失。浅表静脉萎陷，脉搏 110次/分，血压 72/50mmHg，血Na+ 120mmol/L，血浆渗透压 255mOsm/L，血K+ 3.0mmol/L，尿比重﹤1.010，尿钠8mmol/L。

① water loss ≈ sodium loss 3. isotonic dehydration ① water loss ≈ sodium loss ② serum sodium = 130-150mmol/L ③ plasma osmotic pressure:280- 310mOsm/L   1) cause and pathogenesis    ① vomiting; diarrhea; gastrointestinal suction; biliary fistula; intestinal fistula      ② ascitic fluid; pleural effusion

2) effects on body ① slight thirst ② blood volume dehydrated signs; BP   ③ urinary alteration urine specific urine volume gravity [Na+] ------------------------------------------------------------------ early ADH stage ADS  late ADH ------------------------------------------------------------------  3) principles of treatment 补偏低渗液；先补0.9%NaCl

病例2： 患者，女性，38岁，因减肥连续服用泻药一周，现感虚弱乏力，偶有直立性眩晕而入院。 体格检查：体温36.7℃，血压从入院时的110/60mmHg 很快降至 80/50mmHg，心率 100次/分，皮肤弹性差，黏膜干燥，尿量120ml/24h。 实验室检查：血Na+ 140mmol/L，血浆渗透压295mOsm/L，尿比重 1.038，尿钠 6mmol/L。

brain cells swelling (二) 细胞外液容量过多(extracellular fluid excess) 1. water intoxication water intake , total sodium ±; ECF , ICF ; hyponatremia; Serum sodium < 130mmol/L 1) cause      excessive water intake      renal loss (acute renal failure; acute congestive heart failure) 2) effects on body brain cells swelling water moves into cells pulmonary edema 3) principles of treatment diuresis

病例3：患者，女性，因外伤急救误输异型血 200ml后，出现黄疸和无尿。 体格检查：体温37℃，脉搏 80次/分，呼吸 80次/分，血压从入院时的110/60mmHg 很快降至 80/50mmHg。神志模糊，表情淡漠，皮肤黏膜干燥、黄染，静脉塌陷。 实验室检查：血清尿素氮 15.0mmol/L，非蛋白氮 57.12mmol/L，血 K+ 6.7mmol/L。 入院后急速输入5%～10%葡萄糖溶液1500ml，生理盐水500ml后，当晚做血液透析，透析中血压上升并稳定在110～140/70mmHg，透析后查尿素氮为 9.46 mmol/L，非蛋白氮 44.3mmol/L，血 K+ 5.7mmol/L。 患者5天内一直无尿，并逐渐出现明显气喘、心慌、不能平卧，嗜睡、呕吐、头痛、精神错乱症状。查体发现，心率 120次/分，两肺布满湿罗音。血 Na+ 120mmol/L，血浆渗透压 230mOsm/L，红细胞比容 32%。

2. Edema interstitial fluid fluid in the body cavities hydrops fluid in the cells cellular edema (1) pathogenesis 1)imbalance of exchange between intra- and extra- body fluid (retention of water and sodium) basic mechanism: glomerular-tubular imbalance ① GFR acute glomerulonephritis heart failure ② reabsorption of proximal tubule sympathetic nerve filtration fraction ANP reabsorption of water and sodium

③ reabsorption of distal tubule ADH , aldosterone ④ redistribution of renal blood flow sympathetic nerves and renin 2) imbalance of exchange between intra- and extra-vascular fluid ① capillary blood pressure ② plasma colloid osmotic pressure ③ permeability of capillary ④ obstruction of lymph 3) kinds of edema 3. 盐中毒

病例4：患者，女性，因发热、呼吸急促及心悸入院。 体格检查：体温39.6℃，脉搏 161次/分，呼吸 33次/分，血压 110/80mmHg. 口唇发绀，半卧位，颈静脉怒张，心界向两侧扩大，心尖区闻及明显收缩期杂音，两肺闻及广泛湿罗音。肝脾肿大，下肢明显凹陷性水肿，入院诊断为右心衰竭。