Page 96 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

86 ELECTROLYTE DISORDERS

DISORDERS ASSOCIATED WITH [Cl ], as in the case of vomiting of stomach contents

ABNORMAL CL (CORRECTED) or gastric conduit urinary diversions. 18,30,67 Loss of

Corrected Hypochloremia plasma during exercise in greyhounds also leads to
corrected hypochloremia as a result of a greater loss of

Decreased Cl (corrected) is associated with a tendency þ 93
Cl than Na . Interestingly, anticipation of exercise
toward alkalosis (hypochloremic alkalosis) caused by the leads to a corrected hyperchloremia in sled dogs. Chlo-
3
associated increase in SID. 18 Pseudohypochloremia may
ride concentration normalizes after exercise in those
occur whenever chloride ion concentration is measured
dogs. The administration of substances containing
with a technique that is not ion-selective in lipemic or proportionately more sodium than chloride (e.g.,
hyperproteinemic samples. 21,45 Chloride concentration NaHCO 3 ) increases [Na ] without increasing [Cl ],
þ

in lipemic samples (triglyceride concentration >600 therefore causing a decrease in Cl (corrected).
mg/dL) is underestimated by titrimetric methods but Corrected hypochloremia in dogs with hyperadreno-
overestimated when colorimetric methods are used. 45 corticism has been discussed previously. Corrected
Clinical signs associated with pure hypochloremia in dogs
hypochloremia has been observed in dogs 1 week after
and cats have not been reported but probably are related
daily administration of prednisone at a dose of 0.55
to the metabolic alkalosis that accompanies hypo- mg/kg every 12 hours 15 and 3 to 6 days after administra-
chloremia. 17 However, it has been shown that in 77
tion of methylprednisolone acetate (5 mg/kg) to cats.
euvolemic chloride depletion, GFR decreases acutely by
Unlike dogs with hypoadrenocorticism that have
as much as 15% to 20%, probably as a result of changes
corrected hyperchloremia caused by the lack of mineralo-
in tubuloglomerular feedback and internal shifts of corticoids, dogs with gastrointestinal diseases that mimic
fluid out of the ECF. 40,41 The clinical importance of
hypoadrenocorticism (i.e., presence of hyperkalemia
these experimental observations is unknown, but and hyponatremia) 22 tend to develop corrected
hypochloremia itself may potentiate the decrease in GFR hypochloremia. In cats, acute tumor lysis syndrome, 10
associated with hypovolemia in the most common causes primary hypoadrenocorticism, 75 anemia, hemorrhagic
of corrected hypochloremia (e.g., vomiting of stomach 100 13
pleural effusion, and diabetic ketoacidosis have been
contents,therapywithloopdiuretics). Chlorideiondeple-
associated with corrected hypochloremia. Vomiting may
tion also stimulates renin secretion in rats despite concur- have been a contributory factor in the corrected
1
rent volume expansion and potassium infusion. Renin
hypochloremia observed in some of these cats.
release caused by hypochloremia probably is mediated
An increase in renal chloride ion excretion and a
by the macula densa. Any resultant increase in aldosterone
decrease in plasma [Cl ] have been observed in dogs with
secretion would increase potassium excretion in the urine
experimentally induced chronic respiratory acido-
and contribute to hypokalemia. sis. 65,78,87,94 Consequently, patients with chronic hyper-
Corrected hypochloremia may be caused by excessive capnia may be presented with corrected hypochloremia. 50
loss of chloride relative to sodium or by administration Potential causes of corrected hypochloremia are listed in
of substances containing proportionately more sodium Box 4-2, and an algorithm for the differential diagnosis of
than chloride as compared with the normal ECF compo-
corrected hypochloremia is presented in Figure 4-2.
sition. The former can occur with administration of
Treatment of patients with corrected hypochloremia
diuretics that cause chloride ion wasting (e.g., loop
should be directed at correcting the SID. Special atten-
diuretics, thiazides) or when the fluid lost has a high
tion also should be paid to the sodium concentration.
BOX 4-2 Causes of Corrected Hypochloremia
Excessive loss of chloride relative to sodium Hyperadrenocorticism
Gastrointestinal loss Glucocorticoid administration
Vomiting of stomach contents*
Selected gastrointestinal diseases associated with Therapy with solutions containing high sodium
hyperkalemia and hyponatremia in dogs without concentration relative to chloride
hypoadrenocorticism (eg, trichuriasis, salmonellosis, Sodium bicarbonate
perforated duodenal ulcer) Other causes
Renal loss
Exercise in racing Greyhounds
Therapy with thiazides or loop diuretics*
Chronic respiratory acidosis

*Most important causes in small animal practice.