Question 51#

A 24-year-old female with a history of type 1 diabetes mellitus presents to the Emergency Department with vomiting and abdominal pain. Finger-prick testing estimates the blood sugar to be 25 mmol/l. Arterial blood gases record a pH of 7.22. On examination the patient is dehydrated and weighs 80 kg. An intravenous line is sited and bloods are sent. One litre of 0.9% saline is infused and an intravenous insulin pump is set-up.

What rate should insulin be initially given?

A. 10 unit / hour

Correct Answer E: The Joint British Diabetes Societies produced guidelines in 2010 recommending starting the insulin infusion at a rate of 0.1 unit/kg/hour.

Diabetic ketoacidosis:
The most common precipitating factors of diabetic ketoacidosis (DKA) are infection, missed insulin doses and myocardial infarction.

American Diabetes Association diagnostic criteria are as follows:

• Blood glucose >13.8 mmol/l
• PH < 7.30
• Serum bicarbonate <18 mmol/l
• Anion gap > 10
• Ketonaemia 

Management:

• Fluid replacement: most patients with DKA are deplete around 5-8 litres. Isotonic saline is used initially
• Insulin: an intravenous infusion should be started at 0.1 unit/kg/hour. Once blood glucose is < 15 mmol/l an infusion of 5% dextrose should be started
• Correction of hypokalaemia

Complications of DKA and its treatment:

• Gastric stasis
• Cerebral oedema
• Thromboembolism
• Acute respiratory distress syndrome
• Acute renal failure 

Question 52#

A 60-year-old man who is known to have lung cancer comes for review. For the past three weeks he has lost his appetite, has been feeling sick and generally feels tired. On examination he appears to be mildly dehydrated. You order some blood tests: 

• Calcium 3.12 mmol/l
• Albumin 40 g/l
• Glucose (random) 6.7 mmol/l
• Urea 10.2 mmol/l
• Creatinine 115 μmol/l

Which one of his existing medications is most likely to be contributing to his presentation?

A. Amlodipine

Correct Answer C: Thiazides cause hypercalcaemia.

Hypercalcaemia: causes:

The most common causes of hypercalcaemia are malignancy (bone metastases, myeloma, PTHrP from squamous cell lung cancer) and primary hyperparathyroidism.

Other causes include:

• Sarcoidosis*
• Vitamin D intoxication
• Acromegaly
• Thyrotoxicosis
• Milk-alkali syndrome
• Drugs: thiazides, calcium containing antacids
• Dehydration
• Addison's disease
• Paget's disease of the bone**

*other causes of granulomas may lead to hypercalcaemia e.g. Tuberculosis and histoplasmosis.

**usually normal in this condition but hypercalcaemia may occur with prolonged immobilization.

Question 53#

A 42-year-old man presents to his GP feeling generally unwell. For the past three months he has been experiencing daily frontal headaches which have not been helped by regular paracetamol. He has also noticed some unusual symptoms such as his wedding ring no longer fitting, his shoe size apparently increasing and a small amount of milky discharge from both nipples. On examination his blood pressure is 168/96 mmHg.

What is the most likely diagnosis?

A. Phaeochromocytoma

Correct Answer E: 

Acromegaly: features:

In acromegaly there is excess growth hormone secondary to a pituitary adenoma in over 95% of cases. A minority of cases are caused by ectopic GHRH or GH production by tumours e.g. pancreatic.

Features:

• Coarse facial appearance, spade-like hands, increase in shoe size
• Large tongue, prognathism, interdental spaces
• Excessive sweating and oily skin
• Features of pituitary tumour: hypopituitarism, headaches, bitemporal hemianopia
• Raised prolactin in 1/3 of cases --> galactorrhoea
• 6% of patients have MEN-1 

Complications:

• Hypertension
• Diabetes (>10%)
• Cardiomyopathy
• Colorectal cancer

Question 54#

Which one of the following statements regarding the metabolic syndrome is correct?

A. The WHO criteria are used to define impaired glucose tolerance

Correct Answer E: Decisions on primary prevention of cardiovascular disease should be made using standard tools and are not dependant on whether a diagnosis of metabolic syndrome is made. 

Metabolic syndrome:
Unfortunately there are a number of competing definitions of the metabolic syndrome around at the present time. It is thought that the key pathophysiological factor is insulin resistance. 

SIGN recommend using criteria similar to those from the American Heart Association. The similarity of the International Diabetes Federation criteria should be noted. For a diagnosis of metabolic syndrome at least 3 of the following should be identified:

• Elevated waist circumference: men > 102 cm, women > 88 cm
• Elevated triglycerides: > 1.7 mmol/L
• Reduced HDL: < 1.03 mmol/L in males and < 1.29 mmol/L in females
• Raised blood pressure: > 130/85 mmHg, or active treatment of hypertension
• Raised fasting plasma glucose > 5.6 mmol/L, or previously diagnosed type 2 diabetes

The International Diabetes Federation produced a consensus set of diagnostic criteria in 2005, which are now widely in use. These require the presence of central obesity (defined as waist circumference > 94cm for Europid men and > 80cm for Europid women, with ethnicity specific values for other groups) plus any two of the following four factors:

• Raised triglycerides level: > 1.7 mmol/L, or specific treatment for this lipid abnormality
• Reduced HDL cholesterol: < 1.03 mmol/L in males and < 1.29 mmol/L in females, or specific treatment for this lipid abnormality
• Raised blood pressure: > 130/85 mm Hg, or active treatment of hypertension
• Raised fasting plasma glucose > 5.6 mmol/L, or previously diagnosed type 2 diabetes

In 1999 the World Health Organization produced diagnostic criteria which required the presence of diabetes mellitus, impaired glucose tolerance, impaired fasting glucose or insulin resistance, AND two of the following:

• Blood pressure: > 140/90 mmHg
• Dyslipidaemia: triglycerides: > 1.695 mmol/L and/or high-density lipoprotein cholesterol (HDL-C) < 0.9 mmol/L (male), < 1.0 mmol/L (female)
• Central obesity: waist:hip ratio > 0.90 (male), > 0.85 (female), and/or body mass index > 30 kg/m2
• Microalbuminuria: urinary albumin excretion ratio > 20 mg/min or albumin:creatinine ratio > 30 mg/g

Other associated features include:

• Raised uric acid levels
• Non-alcoholic fatty liver disease
• Polycystic ovarian syndrome

Question 55#

A 43-year-old man is found to have a phaeochromocytoma.

Which anti-hypertensive medication should be started first?

A. Propranolol

Correct Answer D: PHaeochromocytoma - give PHenoxybenzamine before beta-blockers.

Phenoxybenzamine is a non-selective alpha-adrenoceptor antagonist and should be started before a betablocker is introduced.

There is ongoing debate about the optimal medical management of phaeochromocytoma, with the suggestion that antihypertensive treatment regimes other than non specific alpha-blockade are just as effective and safe. There are however no trials to provide an answer to this question yet.

Phaeochromocytoma:
Phaeochromocytoma is a rare catecholamine secreting tumour. About 10% are familial and may be associated with MEN type II, neurofibromatosis and von Hippel-Lindau syndrome.

Basics:

• Bilateral in 10%
• Malignant in 10%
• Extra-adrenal in 10% (most common site = organ of Zuckerkandl, adjacent to the bifurcation of the aorta)

Tests:

• 24 hr urinary collection of catecholamines

Surgery is the definitive management. The patient must first however be stabilized with medical management:

• Alpha-blocker (e.g. phenoxybenzamine), given before a
• Beta-blocker (e.g. propranolol)