1
Disorders of Fluid and eletrolyte Metabolism
2005-3-10
Huashan Hospital,Fudan University
2
Water and Sodium Metabolism
? Control of water excretion
? Control of sodium excretion
? Hyponatremia and hypernatremia
3
Control of Water Excretion
? Regulation of thirst
? Antidiuretic hormone
4
Control of Sodium Excretion
? Nephron segmental reabsorption
? Regulation of sodium balance
5
Nephron Segmental reabsorption
? Glomerulotubular balance
? Proximal tubule
? Henle’s loop
? Distal convoluted tubule
? Collecting tubule
6
Regulation of Sodium Balance
? Extrarenal mechanisms
? intrarenal mechanisms
7
Extrarenal mechanisms
? Renal nerves
? Renin-angiotensin System
? Atrial natriuretic peptide
? Vasopressin
? Endogenous Na-K-ATPase inhibitors
8
intrarenal mechanisms
? Renal hemodynamics
? Physical factors
– Prostaglandins
– Kallikrein-kinin system
– Endothelium-derived factors
9
Hyponatremia
? Etiology and classification
? Clinical features
? Treatment
10
Etiology and Classification
? Isotonic hyponatremia
? Hypertonic hyponatremia
? hypotonic hyponatremia
11
Isotonic hyponatremia
? Pseudo-hyponatremia
– Hyperlipidemia
– hyperproteinemia
12
Hypertonic hyponatremia
? Hyperglycemia
? Hypertonic infusion
13
hypotonic hyponatremia
? Hypovolemic hyponatremia
? Hypervolemic hyponatremia
? Isovolemic hyponatremia
14
Hypovolemic hyponatremia
? GI loss
? Skin loss
? 3rd space
? Renal loss
? Adrenal insufficiency
15
Hypervolemic hyponatremia
? CHF
? Liver damage
? nephrosis
16
Isovolemic hyponatremia
? Water intox
? Renal failure
? SIADH
? Reset osmostat
17
Clinical Features
? Neurologic manifestation
– Headache
– Nausea
– Vomiting
– Weakness
– Seizures
– coma
18
Treatment
? Increase serum sodium by 1-2mM/h
? Diuretic--people unable to excrete dilute
urine
19
hypernatremia
? Etiology and classification
? Clinical features
? Treatment
20
Etiology and Classification
? Hypovolemic hypernatremia
? Hypervolemic hypernatremia
? Isovolemic hypernatremia
21
Hypovolemic hypernatremia
? GI loss
? Skin loss
? Renal loss
? Adrenal insufficiency
22
Hypervolemic hypernatremia
? Iatrogenic
? Mineralocort excess
23
Isovolemic hypernatremia
? diabet
? Reset osmostat
? Iatrogenic
? Skin loss
24
Clinical Features
? Neurologic manifesttation
– hypertonia
– hyperreflexia
– Intracranial bleeding
– high fever
– Seizures
– coma
25
Treatment
? decrease serum sodium by 0.5mM/h
? Diuretic
26
potassium Metabolism
? Control of potassium excretion
? Hypokalemia and hyperkalemia
27
Control of potassium Excretion
? Renal potassium handling
? Extrarenal control of potassium
28
Renal Potassium Handling
? Potassium-aldosterone feedback system
? Plasma pH
? Volume expansion-increased urinary flow
rate
? Antidiuretic hormone
29
Extrarenal Control of Potassium
? Insulin
? Catecholamines
? Aldosterone
? Parathyroid hormone
? Acid-base balance
? Drugs
30
hypokalemia
? Etiology
? Clinical features
? Treatment
31
Etiology
? Hypokalemia secondary to transcellular
redistribution
? Hypokalemia with potassium depletion
32
Hypokalemia With Potassium depletion
? Renal loss
? Inadequate intake
? Sweat loss
? Gastrointestinal tract loss
33
Clinical Features
? Fatigue,weakness,myalgia
? Arrhythmias
? Constipation
? Polyuria
? ECG changes
34
Treatment
? Oral replacement
? Therapy for specific causes