Which of the following statements is true regarding hyponatraemia?
Correct Answer C:
Hyponatraemia: Hyponatraemia may be caused by water excess or sodium depletion. Causes of pseudohyponatraemia include hyperlipidaemia (increase in serum volume) or a taking blood from a drip arm. Urinary sodium and osmolarity levels aid making a diagnosis.
Urinary sodium > 20 mmol/l: Sodium depletion, renal loss (patient often hypovolaemic):
Patient often euvolaemic:
Urinary sodium < 20 mmol/l:
Water excess (patient often hypervolaemic and oedematous):
You are performing a study of blood pressure readings in patients with chronic kidney disease. Assuming that the results are normally distributed, what percentage of values lie within two standard deviations of the mean blood pressure reading?
Correct Answer A:
Normal distribution: The normal distribution is also known as the Gaussian distribution or 'bell-shaped' distribution. It describes the spread of many biological and clinical measurements.
Properties of the Normal distribution:
Standard deviation:
Doxazosin is a:
Correct Answer A: Doxazosin is an alpha-1 adrenoceptor antagonist used in the treatment of hypertension and benign prostatic hypertrophy.
Adrenoceptor antagonists: Alpha antagonists:
Beta antagonists:
A new oral-hypoglycaemic is being developed. A number of different study types are considered to demonstrate efficacy in reducing the HbA1c.
Which one of the following study designs would require the most patients to produce a significant result?
Correct Answer C: As a superiority trial compares the new drug with an existing treatment, which would also lower HbA1c, a large sample size is required to demonstrate a significant difference.
Study design: new drugs: When a new drug is launched there are a number of options available in terms of study design. One option is a placebo controlled trial. Whilst this may provide robust evidence it may be considered unethical if established treatments are available and it also does not provide a comparison with standard treatments.
If a drug is therefore to be compared to an existing treatment a statistician will need to decide whether the trial is intended to show superiority, equivalence or non-inferiority:
It should be remembered that drug companies may not necessarily want to show superiority over an existing product. If it can be demonstrated that their product is equivalent or even non-inferior then they may compete on price or convenience.
Which one of the following statements regarding glucagon-like peptide-1 (GLP-1) is incorrect?
Correct Answer B: Decreased levels of GLP-1 are seen in type 2 diabetes mellitus.
Diabetes mellitus: GLP-1 and the new drugs: A number of new drugs to treat diabetes mellitus have become available in recent years. Much research has focused around the role of glucagon-like peptide-1 (GLP-1), a hormone released by the small intestine in response to an oral glucose load.
Whilst it is well known that insulin resistance and insufficient B-cell compensation occur other effects are also seen in type 2 diabetes mellitus (T2DM). In normal physiology an oral glucose load results in a greater release of insulin than if the same load is given intravenously - this known as the incretin effect. This effect is largely mediated by GLP-1 and is known to be decreased in T2DM. Increasing GLP-1 levels, either by the administration of an analogue or inhibiting its breakdown, is therefore the target of two recent classes of drug.
Glucagon-like peptide-1 (GLP-1) mimetics (e.g. exenatide):
NICE guidelines on the use of exenatide:
The Medicines and Healthcare products Regulatory Agency has issued specific warnings on the use of exenatide:
Dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g. Vildagliptin, sitagliptin):
NICE guidelines on DPP-4 inhibitors:
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