The nicotinic acetylcholine receptor is an example of a:
Correct Answer A:
Membrane receptors: There are four main types of membrane receptor: ligand-gated ion channels, tyrosine kinase receptors, guanylate cyclase receptors and G protein-coupled receptors:
1- Ligand-gated ion channel:
2- Tyrosine kinase receptors:
3- Guanylate cyclase receptors:
4- G protein-coupled receptors:
A 72-year-old woman who takes bendroflumethiazide for hypertension is admitted to the Emergency Department. Admission bloods show the following:
Which one of the following ECG features is most likely to be seen?
Correct Answer E: Hypokalaemia - U waves on ECG. Hypokalemia may been defined as a potassium level lower than 3.5 mEq/L. Moderate hypokalemia is a serum level of < 3.0 mEq/L. Severe hypokalemia is defined as a level < 2.5 mEq/L.
J waves are seen in hypothermia whilst delta waves are associated with Wolff Parkinson White syndrome.
ECG features of hypokalaemia:
ECG changes according to Potassium serum levels.
Vitamin D causes which one of the following:
Correct Answer A: Vitamin D increases plasma calcium and plasma phosphate levels by promoting renal tubular absorption and gut.
absorption of calcium and increasing renal phosphate reabsorption.
Calcium metabolism: The two hormones which primarily control calcium metabolism are:
Other hormones include:
Actions of parathyroid hormone:
Which one of the following is least associated with hypercalcaemia?
Correct Answer E: One of the key differentiating features between monoclonal gammopathy of uncertain significance (MGUS) and myeloma is the absence of complications such as immune paresis, hypercalcaemia and bone pain.
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:
*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
A new test to screen for pulmonary embolism (PE) is used in 100 patients who present to the Emergency Department. The test is positive in 30 of the 40 patients who are proven to have a PE. Of the remaining 60 patients, only 5 have a positive test.
What is the sensitivity of the new test?
Correct Answer E: A contingency table can be constructed from the above data, as shown below:
The sensitivity is therefore= 30 / (30 + 10) = 75%
Screening test statistics:
It would be unusual for a medical exam not to feature a question based around screening test statistics. The available data should be used to construct a contingency table as below: TP = true positive; FP = false positive; TN = true negative; FN = false negative:
The table below lists the main statistical terms used in relation to screening tests:
Positive and negative predictive values are prevalence dependent. Likelihood ratios are not prevalence dependent.
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