Endocrine emergencies

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Chapter 26 Endocrine emergencies

EMERGENCIES IN PATIENTS WITH DIABETES

Diabetes is a disorder of glucose metabolism due to a relative (type 2) or absolute (type 1) insulin deficiency. With the rising rate of obesity in the community, diabetes is becoming increasingly common, and type 2 rather than type 1 diabetes is now often seen in young patients. Diabetic patients may present to the emergency department with acute life-threatening derangements of glucose metabolism, with complications related to long-standing diabetes, or with unrelated health problems which require concurrent management of their diabetes.

Diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is due to insulin deficiency resulting in acidosis with ketosis, hyperglycaemia and fluid and electrolyte losses. It occurs in patients with type 1 (insulin-dependent) diabetes and may be the presenting problem in patients with previously undiagnosed diabetes. The principles in assessment and management of DKA are identifying and treating the precipitating cause, assessing the severity of the illness, correcting fluid and electrolyte disturbances, and administering insulin.

Management

Patients with DKA are often extremely ill and should be initially managed in an area of the emergency department with continuous ECG and oximetry monitoring, and regular blood pressure measurements. If there is a depressed level of consciousness the patient requires supportive airway management and may need intubation. Ongoing regular measurement of BSL and serum K+ should continue throughout treatment.

Fluid and electrolyte therapy

All patients with DKA are volume depleted and require rehydration with intravenous fluids. Hypotension (systolic BP < 100 mmHg) should be treated with boluses of normal saline up to 2000 mL until blood pressure has improved. In the normotensive patient, 1 litre of normal saline should be given over the first hour, followed by a second litre over the next 2 hours. Subsequent fluid therapy will be guided by clinical assessment of pulse rate and hydration status, but most patients will require 5–8 litres of fluid over the first 24 hours. A dextrose-containing solution should be commenced once the BSL falls below 15 mmol/L, in addition to ongoing sodium requirements.

Potassium depletion is a feature of DKA, even in the presence of an initial elevated serum K+. Serum potassium should be measured as soon as possible and is often available on the initial blood gas. The administration of intravenous fluids and insulin will rapidly lower the measured K+. If the initial K+ is > 5.5 mmol/L, the level should be rechecked every 30–60 minutes as it will inevitably fall as a consequence of rehydration. Table 26.1 outlines the rate of potassium replacement. Monitoring of K+ levels every 1–2 hours is essential during the initial phase of treatment.

Table 26.1 Guide to potassium replacement in DKA

Serum K+, mmol/L Replacement therapy
> 5.5 Nil—repeat test in 1 h
3.5–5.5 KCl 5–10 mmol/h
< 3.5 KCl 20 mmol/h, cardiac monitoring and central line

Phosphate and magnesium levels are commonly low in DKA; however, there is no evidence to support the routine replacement of these electrolytes. Intravenous bicarbonate is of no proven benefit in patients with DKA as the acidosis usually improves with rehydration and insulin therapy. Bicarbonate should not be given without consulting a critical care specialist or endocrinologist. The measured sodium level should be corrected for the elevated glucose (true sodium = measured sodium + [glucose (mmol/L) ÷ 4]) as the high BSL will artefactually dilute the sodium.

Hyperosmolar hyperglycaemic non-ketotic state (HHNS)

This condition occurs primarily in older patients with non-insulin-dependent diabetes, although it has several clinical features in common with diabetic ketoacidosis. It is characterised by relative, rather than absolute, insulin deficiency leading to hyperglycaemia, hyperosmolarity and dehydration, with little or no acidosis or ketosis. The goals of therapy are identification and treatment of the precipitating event, controlled correction of fluid and electrolyte abnormalities, and correction of hyperglycaemia.

Assessment

HHNS is characterised by non-specific signs such as confusion, vomiting and weight loss, developing over days to weeks in elderly patients with undiagnosed or poorly controlled diabetes. Polyuria and polydipsia are not universally present. There are many possible precipitating events which are summarised in Box 26.2. These patients often have multiple comorbidities and may be on multiple medications.

Physical examination is focused on assessing the degree of dehydration and looking for evidence of a precipitating cause. The diagnosis is confirmed by the presence of severe hyperglycaemia (often > 50 mmol/L) and serum hyperosmolarity (> 350 mosm/L), with minimal acidosis (pH > 7.3).

Important early investigations include: