Patients with DKA present with often vague complaints such as nausea, fatigue, or generalized weakness. Vomiting and abdominal pain may be present. Altered mental status

 

Patients with DKA present with often vague complaints

such as nausea, fatigue, or generalized weakness. Vomiting

and abdominal pain may be present. Altered mental status

(AMS) also occurs in severe disease and is closely correlated

with a high serum osmolality.

In patients with HHS, AMS is the most common presentation. Additional neurologic complaints include seizures,

hemiparesis, and coma. Coma is present in only 10% of cases.

� Physical Examination

Patients with hyperglycemia or diabetic ketosis may exhibit

evidence of mild dehydration.

In DKA, vital signs are often abnormal, with tachycardia and tachypnea, with characteristic Kussmaul respira ­

tions. If there is severe dehydration or sepsis, hypotension or

hyperthermia may be present. Hypothermia is a poor prognostic sign. Fruity odor on the breath owing to ketonemia

may be present. Evidence of dehydration includes dry

mucous membranes, decreased skin turgor, and tachycardia.

Urine output may be maintained because of the ongoing

osmotic diuresis. Physical examination may reveal a source

of infection such as pneumonia, pyelonephritis, or cellulitis.

In HHS, physical examination findings are similar to

those of DKA. Patients usually show evidence of severe dehydration. AMS is a hallmark. A focused neurologic examination is indicated in these patients to detect focal neurologic

deficits. Searching for other precipitating causes that can be

seen on physical examination such as infection is imperative.

DIAGNOSTIC STUDIES

� Laboratory

The first most important test to obtain is a fingerstick

blood glucose at the bedside to rapidly establish the

presence of hyperglycemia. The accuracy of these machines

is known to decrease at extreme elevations, and many will

not read values >600 mg/dL.

Obtain serum electrolytes, renal function, serum

osmolality, and urine ketones. In DKA, the bicarbonate level

will be low, and there will be an elevated anion gap. The

serum potassium level is frequently elevated as a result of

acidemia, causing a shift of potassium into the extracellular

space. As treatment is initiated, potassium is drawn back

into the cells, exposing a total body potassium that is low.

Sodium concentration is also frequently low, usually artificially, because water is drawn out of the intracellular space

by the elevated glucose. To account for this, the sodium

concentration is corrected by adding 1.6 mEq/L (correction

factor) for every 100 mg!dL increase in the glucose. A correction factor of 2.4 mEq/L is more accurate for glucose

levels >400 mg!dL. In HHS, the measured (uncorrected)

sodium concentration, glucose level, and blood urea nitrogen (BUN) are used to calculate the serum osmolality:

Serum osmolality (mOsm/L) = 2(Na) + glucose/ IS

+ BUN/2.8

The nitroprusside test used for the detection of ketones

on urinalysis identifies acetoacetate and acetone but does

not detect �-hydroxybutyrate. In DKA, there is a predominance of �-hydroxybutyrate. Despite some earlier concerns

that urine ketones could be falsely normal in DKA because

of the predominance of �-hydroxybutyrate, this has not

turned out to be the case in clinical practice. Urine ketones

can be used as an accurate screen for the presence of serum

ketones. However, it should be remembered that as treatment ensues, a shift to acetoacetate and acetone makes

urine ketones more positive despite adequate t reatment.

The pH of a venous blood gas is an accurate estimation

of the arterial pH in DKA and can be used to guide management. To determine complex acid-base disorders, an

arterial blood gas can be obtained, but this test rarely

impacts treatment decisions.

When there is suspicion of an underlying infection, blood

cultures, urinalysis, and urine culture should also be obtained.

� Electrocardiogram

An electrocardiogram is obtained to evaluate for signs of

hyperkalemia or cardiac ischemia.

� Imaging

A chest x-ray is indicated when clinical symptoms suggest

pneumonia or another concomitant cardiopulmonary illness.

Head computed tomography scan is obtained to rule out

precipitating cranial pathology (ie, stroke, intracranial hem ­

orrhage) if the patient has AMS.

MEDICAL DECISION MAKING

The differential diagnosis of DKA includes all causes of

metabolic acidosis with an anion gap (methanol ingestion,

uremia or renal failure, isoniazid, lactic acidosis, ethylene

glycol ingestion, alcoholic ketoacidosis, salicylate toxicity).

History and laboratory data should provide the clues to

make the appropriate diagnosis. In determining the pre ­

cipitant ofDKA, the differential diagnosis includes sources

of infection, cerebral vascular accident, and acute

CHAPTER 66

Urine for ketones, serum electrolytes

glucose, ± blood gas ± serum Osmolal ity

Figure 66-1. Diabetic emergencies diag nostic algorithm. AG, anion gap; H HS, hyperg lycemic hyperosmolar state; OSM, Osmolal ity.

coronary syndrome. Noncompliance with insulin therapy

is a diagnosis of exclusion.

Often presenting complaints of patients with DKA

include abdominal pain, and thus the differential diagnosis

also includes appendicitis, pancreatitis, and gastroenteritis.

These are ruled in or out primarily based on history and

physical exam.