Question 131#

Which of the following secondary causes of hyperlipidaemia result in predominantly hypercholesterolaemia, as opposed to hypertriglyceridaemia? 

A. Hypothyroidism

Correct Answer A: Hypercholesterolaemia rather than hypertriglyceridaemia: nephrotic syndrome, cholestasis, hypothyroidism.

Hyperlipidaemia: secondary causes:
Causes of predominantly hypertriglyceridaemia:

• Diabetes mellitus (types 1 and 2)
• Obesity
• Alcohol
• Chronic renal failure
• Drugs: thiazides, non-selective beta-blockers, unopposed oestrogen
• Liver disease

Causes of predominantly hypercholesterolaemia:

• Nephrotic syndrome
• Cholestasis
• Hypothyroidism

Question 132#

A 65-year-old man known to have a carcinoid tumour of the appendix is found to have hepatic metastases.

If the patient develops carcinoid syndrome, which one of the following symptoms is most likely to occur first?

A. Facial flushing

Correct Answer A: Carcinoid tumours

Carcinoid syndrome:

• Usually occurs when metastases are present in the liver and release serotonin into the systemic circulation
• May also occur with lung carcinoid as mediators are not 'cleared' by the liver

Features:

• Flushing (often earliest symptom)
• Diarrhoea
• Bronchospasm
• Hypotension
• Right heart valvular stenosis (left heart can be affected in bronchial carcinoid)
• Other molecules such as ACTH and GHRH may also be secreted resulting in, for example, Cushing's syndrome
• Pellagra can rarely develop as dietary tryptophan is diverted to serotonin by the tumour

Investigation:

• Urinary 5-HIAA
• Plasma chromogranin A y

Management:

• Somatostatin analogues e.g. octreotide
• Diarrhoea: cyproheptadine may help

Question 133#

Which one of the following statements regarding the management of diabetes mellitus during pregnancy is incorrect?

A. A previous macrosomic baby is a risk factor for gestational diabetes

Correct Answer D: There is increasing evidence that metformin is safe during pregnancy.

Pregnancy: diabetes mellitus:
Diabetes mellitus may be a pre-existing problem or develop during pregnancy, gestational diabetes. It complicates around 1 in 40 pregnancies.

Risk factors for gestational diabetes:

• BMI of > 30 kg/m²
• Previous macrosomic baby weighing 4.5 kg or above
• Previous gestational diabetes
• First-degree relative with diabetes
• Family origin with a high prevalence of diabetes (South Asian, black Caribbean and Middle Eastern)

Screening for gestational diabetes:

• If a women has had gestational diabetes previously an oral glucose tolerance test (OGTT) should be performed at 16-18 weeks and at 28 weeks if the first test is normal
• Women with any of the other risk factors should be offered an OGTT at 24-28 weeks
• Currently the same WHO diagnostic criteria are used as for non-pregnant patients. There is however increasing evidence that a lower threshold should be used as treating borderline patients improves both maternal and neonatal outcomes

NICE issued guidelines on the management of diabetes mellitus in pregnancy in 2008 Management of pre-existing diabetes:

• Weight loss for women with BMI of > 27 kg/m²
• Stop oral hypoglycaemic agents, apart from metformin, and commence insulin
• Folic acid 5 mg/day from pre-conception to 12 weeks gestation
• Detailed anomaly scan at 18-20 weeks including four-chamber view of the heart and outflow tracts
• Tight glycaemic control reduces complication rates
• Treat retinopathy as can worsen during pregnancy

Management of gestational diabetes:

• Responds to changes in diet and exercise in around 80% of women
• Oral hypoglycaemic agents (metformin or glibenclamide) or insulin injections are needed if blood glucose control is poor or this is any evidence of complications (e.g. macrosomia)
• There is increasing evidence that oral hypoglycaemic agents are both safe and give similar outcomes to insulin
• Hypoglycaemic medication should be stopped following delivery
• A fasting glucose should be checked at the 6 week postnatal check

Question 134#

Each one of the following is a cause of nephrogenic diabetes insipidus, except: 

A. Hypocalcaemia

Correct Answer A: 

Diabetes insipidus:
Diabetes insipidus (DI) is a condition characterized by either a deficiency of antidiuretic hormone, ADH, (cranial DI) or an insensitivity to antidiuretic hormone (nephrogenic DI).

Causes of cranial DI:

• Idiopathic
• Post head injury
• Pituitary surgery
• Craniopharyngiomas
• Histiocytosis X
• DIDMOAD is the association of cranial Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness (also known as Wolfram's syndrome)

Causes of nephrogenic DI:

• Genetic: the more common form affects the vasopression (ADH) receptor, the less common form results from a mutation in the gene that encodes the aquaporin 2 channel
• Electrolytes: hypercalcaemia, hypokalaemia
• Drugs: demeclocycline, lithium
• Tubulo-interstitial disease: obstruction, sickle-cell, pyelonephritis

Features:

• Polyuria
• Polydipsia

Investigation:

• High plasma osmolarity, low urine osmolarity
• Water deprivation test

Question 135#

A 25-year-old man with a family history of multiple endocrine neoplasia type 1 is reviewed in clinic.

What is the single most useful investigation to monitor such patients?

A. Short synacthen test

Correct Answer C: The high incidence of parathyroid tumours and hypercalcaemia make serum calcium a useful indicator of MEN type 1 in suspected individuals.

Multiple endocrine neoplasia:
The table below summarizes the three main types of multiple endocrine neoplasia (MEN):

MEN is inherited as an autosomal dominant disorder