Effect of rapid intravenous administration of 50% dextrose solution on phosphorus homeostasis in postparturient dairy cows.
BACKGROUND
Dextrose is commonly administered to postparturient dairy cows, which often have low plasma phosphorus concentration ([P]) as a result of anorexia and sudden onset of lactation. Intravenous (IV) dextrose administration causes hypophosphatemia in other species.


OBJECTIVE
Bolus administration of dextrose to postparturient dairy cows results in a transient decrease in plasma [P].


METHODS
Six healthy postparturient dairy cows.


METHODS
Using a crossover design, cows were administered 500 mL of 50% dextrose solution IV or a sham treatment. Plasma concentrations of glucose ([glucose]), immunoreactive insulin ([IRI]), and phosphorus were monitored for 12 hours after each treatment. Urine [P], [glucose], and volume and salivary [P] were also determined.


RESULTS
Plasma [glucose], [IRI], and [P] were stable during sham treatment. Plasma [P] decreased rapidly after dextrose administration, dropping by 35% in 1 hour and remaining below baseline for 90 minutes. Salivary [P], urine [P], and urine volume per hour remained stable after dextrose administration, but glucose was detected in urine for up to 6 hours. The amount of glucose excreted in urine in 12 hours (11.9+/-4.5 g) was less than 5% of the administered dose. Regression analysis revealed a stronger association between plasma [P] and [IRI] than between plasma [P] and [glucose], suggesting that hyperinsulinemia drove the hypophosphatemia.


CONCLUSIONS
Results indicate that low plasma [P] should be expected in cows that have received IV dextrose within 1 hour before blood sampling. Caution is advised when administering dextrose solution to cows already at risk of hypophosphatemia.
Grünberg
Walter
W
Department of Veterinary Clinical Medicine University of Illinois, Urbana, IL 61802, USA.
Morin
Dawn E
DE
Drackley
James K
JK
Constable
Peter D
PD
D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D002417:Cattle / Q000097:blood* / Q000378:metabolism; D018592:Cross-Over Studies; D003612:Dairying; D005260:Female; D005947:Glucose / Q000493:pharmacokinetics*; D006029:Glycosuria / Q000662:veterinary; D007262:Infusions, Intravenous / Q000662:veterinary; D007328:Insulin / Q000378:metabolism; D007774:Lactation / Q000378:metabolism*; D010758:Phosphorus / Q000097:blood* / Q000652:urine; D049590:Postpartum Period / Q000097:blood*; D011247:Pregnancy; D016482:Urinalysis / Q000662:veterinary
D001786:Blood Glucose; D007328:Insulin; D010758:Phosphorus; D005947:Glucose