Spontaneous Hypoglycaemia

Autonomic

Neuroglycopenic

Sweating

Dizziness

Trembling

Confusion

Warmness

Tiredness

Anxiety

Difficulty with speaking

Hunger

Headache

Pounding heart

Blurred vision

Weakness

Difficulty in concentrating

The next group of questions relates to possible underlying causes of hypoglycaemia and in that regard a detailed previous medical history and systematic enquiry are crucial. The most important question to ask is “What medication are you taking?” Clearly the most common cause of hypoglycaemia is insulin or sulfonylurea therapy for diabetes, but even in people without diabetes, drug therapy is a very important precipitating factor (Table 18.2). The other potential causes of hypoglycaemia relate to the context of the patient. The differential diagnosis is completely different in a hospitalised patient, where liver disease and sepsis predominate, compared with an out-patient setting. Moreover, there are definite geographical variations in the aetiology of hypoglycaemia – falciparum malaria and consumption of unripe ackee fruit are common causes in some parts of the world.

Table 18.2

Differential diagnosis of spontaneous hypoglycaemia according to insulin and C-peptide levels

High insulin and high c–peptide

Insulinoma

Sulfonylureas

Pentamidine

Hyperinsulinaemia of infancy

High insulin and low c–peptide

Exogenous insulin

Low insulin and low c–peptide

Alcohol

Drugs, e.g., quinine, quinidine

Critical illness, e.g., septicaemia, liver failure, renal failure, falciparum malaria

Hypopituitarism (rare)

Adrenocortical failure, especially in children

Non-islet tumour hypoglycaemia

Inborn errors of metabolism

In this case, the patient reports that she has noticed a change in her symptom profile. She does not sweat as nearly as much now during episodes as she did when they first started happening. She does not take any regular medication. The only previous history of note is that 4 years previously she had developed lower abdominal pain and was found to have a “growth” in her pelvis that was successfully removed. On systems enquiry, she does say that she has lost about 6 kg in weight over the last 6 months and that she has been experiencing some discomfort in the right upper quadrant of her abdomen.

What are the signs to look for?

This history is becoming increasingly worrying. Patients with insulinomas invariably present with weight gain, because they have been eating more than normal to avoid hypoglycaemia. Weight loss, in the context of a previous tumour, is not good news. It is unlikely that she will be hypoglycaemic at the time you see her in clinic. Usually clinical examination of a patient with suspected spontaneous hypoglycaemia is remarkably unrewarding, but in this situation we need to look for signs of potential malignant disease.

Examination of the lady’s abdomen, reveals 4 cm of palpable hepatomegaly with a worryingly coarse feel to the liver.

Summary of Symptoms and Signs

This lady has presented with symptoms consistent with a hypoglycaemic disorder and signs of a metastatic cancer. We need to find out urgently what the nature was of the tumour removed 4 years ago; we need to confirm the occurrence of hypoglycaemia and we need to establish its aetiology. She could have a malignant insulinoma, but that would mean the previous tumour is unrelated. Alternatively, she could have significant hepatic impairment, secondary to cancer, with hypoglycaemia a consequence of depleted glucagon reserves. However, one would expect her to be more unwell in this situation and possibly even jaundiced. Finally, she could have non-islet cell tumour hypoglycaemia.

What diagnostic tests are required?

In reality, with a patient of this sort, investigations would happen in parallel rather than in series. However, for the sake of clarity, they will be presented in a logical sequence.

Liver function tests showed only marginal elevation of alkaline phosphatase and gamma GT. Bilirubin was not elevated and albumin was 34 g/dl. This makes hypoglycaemia secondary to loss of hepatic reserve unlikely.

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