EMQs in Clinical Medicine.pdf - Peshawar Medical College

Hypercalcaemia – answers 207
The water deprivation test is used to confirm diagnosis. A normal person
will maintain his or her plasma osmolality and increase the urine osmolality
(ADH working normally to maintain homoeostasis) in response to
water deprivation. However, in a cranial DI patient there is a rise in
plasma osmolality with production of dilute urine until exogenous ADH
(vasopressin) is given.
In a nephrogenic DI patient the same plasma and urine osmolality
changes occur but there is no response to the exogenous vasopressin.
A 45-year-old man with type 2 diabetes mellitus presents with
drowsiness and dehydration. Plasma sodium is 158 mmol/l and
glucose 40 mmol/l.
L Hyperosmolar non-ketotic coma (HONK) is a complication of type 2
diabetes. The patient usually has a history of poorly controlled diabetes
or is undiagnosed before presentation. There is no acidosis. Appropriate
first-line management of this patient would involve fluid replacement
with 0.9 per cent saline. Insulin must be used with care because, if the
plasma glucose falls too rapidly, there is a risk of a rapid change in
osmolality causing cerebral oedema.
Anticoagulation is indicated as a result of the risk of thrombosis.
J
C
A 50-year-old person with type 1 diabetes and hyperlipidaemia has a
mild hyponatraemia. Plasma sodium 125 mmol/l.
Pseudohyponatraemia refers to a spuriously low plasma sodium concentration
caused by hyperlipidaemia/hyperproteinaemia.
Hyponatraemia associated with heavy proteinuria in a 55-year-old
woman on long-term penicillamine treatment for rheumatoid arthritis.
In the nephrotic syndrome there is hypervolaemia, usually with clinically
evident oedema, e.g. pedal oedema. Immune complex glomerulonephritis
is common with penicillamine treatment and causes a mild proteinuria.
The drug must be stopped but can often be resumed at a lower dose once
the problem has resolved. However, heavy proteinuria is more serious
and necessitates permanent withdrawal of treatment.
82 Hypercalcaemia
Answers: F A K E G
F
An 80-year-old woman presents with weight loss and back pain.
Investigations reveal an elevated erythrocyte sedimentation rate (ESR)
and marked excretion of immunoglobulin light chains in the urine.
Even in the absence of the IgG chains in the urine, there are certain red
flags here that suggest a sinister cause for the back pain, e.g. weight loss
and elevated ESR. More than 1 g light chains excreted in the urine per