Chloride Disorders Flashcards
Chloride constitutes approximately what percentage of the anions in plasma?
2/3rds
What is a normal chloride conc in dogs and cats?
Dogs - 110
Cats 120mEq/L
Chloride Metabolism
How is chloride absorbed in the jejunum?
Follows the absorption of sodium - is paracellular and due to the need to maintain electroneutrality
What percentage of enterally absorbed chloride is absorbed in the colon?
90% - is highly efficient.
Of filtered chloride how much is resorbed in the proximal tubules?
Of filtered chloride, approximately 50% to
60% is reabsorbed by the proximal convoluted and straight
tubules. Chloride reabsorption occurs transcellularly in
the thick ascending limb of Henle’s loop, leading to the
generation of a lumen-positive transepithelial voltage
Sodium is reabsorbed transcellularly or paracellularly, and
the transepithelial voltage drives the latter process. Chloride ion delivery is the rate-limiting step in this process, and net sodium chloride (NaCl) transport increases directly with fluid [Cl] concentration. Loop diuretics such as furosemide and bumetanide act in the loop of Henle by competing for the chloride site on the Na-K - 2Cl carrier.
Chloride and acid base balance
What must be done to correct a hypochloraemic alkalosis?
Provision of volume –> but most importantly provision of chloride
The principal mechanisms by which the
kidneys correct metabolic alkalosis probably operate in
the collecting ducts, especially in the cortical segment,
where HCO3
- can either be secreted or reabsorbed.
chloride
alone is essential for correction of the hypochloremic
alkalosis and that it does so by a renal mechanism. Volume
depletion is a common but not essential feature of the
maintenance phase of alkalosis, and its persistence does
not preclude correction of alkalosis. If adequate chloride
is provided, restoration of depleted volume, however,
may hasten correction of alkalosis by increasing the
GFR and decreasing proximal tubular reabsorption of
fluid and bicarbonate.39,40 The manner by which exogenous
Cl
repletion is detected and the kidneys are signaled
to excrete HCO3
, and the cellular mechanisms
by which these events occur in the various nephron
segments, remain to be determined
What is the main way in which chloride is involved in the renal compensation of an acidosis?
Enhanced excretion of NH4Cl . This subsequently increases SID
Ultimately Chloruresis, negative chloride balance,
enhanced fractional and absolute bicarbonate reabsorption,
and enhanced net acid excretion typically are
associated with the renal response to chronic respiratory
acidosis
Clinical Approach to Chloride Disorders
What is the value of corrected chloride?
Allows adjustement of chloride for gain or loss of free water
Corr Cl = Cl- measured x (Na - normal/Na -measured)
Corrected Hypochloremia
What acid base abnormality will be seen with corrected hypochloraemia?
Alkalosis and an increased SID
What renal physiologic consequence of hypochloraemia may be seen?
A decrease in GFR of 15-20% probably as a result of changes
in tubuloglomerular feedback and internal shifts of
fluid out of the ECF
May compound renal consequences of fluid loss too.
What may cause hypochloraemia
Gastrointestinal loss
- Vomiting of stomach contents*
- Selected gastrointestinal diseases associated with
hyperkalemia and hyponatremia in dogs without
hypoadrenocorticism (eg, trichuriasis, salmonellosis,
perforated duodenal ulcer)
Renal loss
- Therapy with thiazides or loop diuretics*
- Chronic respiratory acidosis
- Hyperadrenocorticism
- Glucocorticoid administration