Endocrine emergencies (Proceedings)

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Endocrine emergencies (Proceedings)

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Oct 01, 2008



Insulin therapy should be started after the animal has been on IV fluids a short time (4-6 hrs). This will not only decease the blood glucose, but also improve perfusion for better insulin absorption. Animals that present as sick DKAs (vomiting, depressed, significant acidosis) should not be treated initially with insulin via the subcutaneous route. The intramuscular or an intravenous continuous infusion routs are the more preferred. Regular insulin is used because it has a rapid onset and a brief duration of effect, allowing the clinician to titrate the dose to desired effect. Insulin is started, not only to decrease the blood glucose, but to help resolve the ketonemia. An initial dose of 0.2 U/kg IM every 6 hours is a good starting dose. The blood glucose should not be dropped faster than 50 mg/dl/hr or significant osmotic shifts could occur. A CRI of regular insulin can also be done. A starting dose is 2.2 U/kg/day. This regime of using the CRI requires strict supervision and a very informed support staff. The goal is to keep the BG in the 100-200 mg/dl range. Below is an example of a sliding insulin scale for a sick DKA dog.

Monitor the body weight, PCV/TS, electrolytes (including phos, Mg++), blood gas and urine output to ensure fluid balance at least twice daily. A central line (ideally jugular) is ideal for monitoring CVP and serial sampling of blood glucose (every 6 hrs), electrolytes and acid base status. The use of broad spectrum antibiotics should be used due to high incidence of infection in these patients (get urine culture first). The urine should be dipped daily for glucose and ketones.

Hyperosmolar Nonketotic DM (HONKDM)

This is a less common complication of diabetes than DKA in frequency. Although, a less frequent complication it is clinically more severe. Unlike DKA, there is a relative insulin deficiency and some insulin is still present. This is why there is little or no ketones present with HONKDM. The diagnosis is made by the presence of severe hyperglycemia (> 600 mg/dl), hyperosmolarity (> 330 mOsm/kg), and lack of ketones. The extreme volume contraction and hyperglycemia cause significant hyperosmolarity, leading to dehydration and mental dullness. The effective osmolarity is defined by 2[Na] + Glu/18, and BUN and potassium are left out of the equation since they are not effective osmoles.

The treatment is similar as for DKA, but due to the severity of the hyperosmolarity and significant hyperglycemia treatment should be performed slowly and imbalances corrected gradually. If the osmolarity is corrected to fast, then there is significant risk of the patient developing cerebral edema. The goal is to correct the imbalances over 36-48 hours to prevent this complication. Decrease the osmolarity by 0.5/hour.

Addisonian crisis

The initial diagnosis of Addison's disease is usually made when a patient presents for a crisis. These dogs are typically bradycardic, hypotensive, weak, dehydrated, hypoglycemic, low cholesterol, hyponatremic, hyperkalemic, hypercalcemic, low albumin, lack of stress leukogram and varying azotemia. The weakness or collapse often results from hypovolemia and an inability to deal with stress. The bradycardia is due to the increased potassium, and the hypotension is due to the lack or cortisol required for adequate adrenergic receptor function. Please see reference of review for complete explanation of abnormalities.

Diagnosis

The diagnosis is made from performing an ACTH stimulation tests. Often treatment is started pending the results, although a Na:K ratio of ≤ 24 is 79% sensitive and 100% specific for the diagnosis of Addison's.