The most common psychiatric disturbance associated with Cushing’s disease is:
A. Cushing’s syndrome is very frequently, although not invariably, associated with depression. Nearly 40% of cases in one series of observation had depression whereas only 3% had mania. It is claimed that the predominance of pure depressive disorders may be a result of publication bias; controlling for this yields mixed anxiety and depression as the most common psychiatric disturbance in Cushing’s syndrome. Depression in Cushing’s syndrome may occur as a prodrome even before the medical disorder is diagnosed; the phenomenology may differ from primary major depression in that the symptoms are intermittent when associated with Cushing’s syndrome. Psychosis occurs more commonly in association with affective states; isolated schizophreniform psychosis is rare. Delirium may occur in 15–20% of patients.
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Polyuria can be a troublesome side-effect with lithium therapy.
Which of the following is NOT correct with response to lithium-related polyuria?
C. Lithium-related polyuria and polydipsia are seen in nearly one-third of those treated. Polyuria is usually reversible in the early stages but may become obstinate the longer the therapy lasts. When a once-daily preparation of lithium is used instead of multiple divided doses, the frequency of polyuria seems to be less, but a direct correlation between plasma peaks and polyuria is not clearly demonstrated in clinical samples. Dose reduction or use of amiloride can be tried in those who have troublesome levels of polyuria. Amiloride has relatively less propensity to cause electrolyte disturbances when co-prescribed with lithium than with other diuretics.
Which of the following electrolyte disturbances simulate lithium-induced changes in electrocardiogram?
D. Lithium exerts minimal cardiac effects at therapeutic doses in most patients. It most commonly produces benign reversible T-wave changes (including inversion and flattening) in the resting electrocardiogram (ECG). These hypokalaemia-like changes are seen in approximately 20–30%of patients treated with lithium. ECG abnormalities of clinical significance are mainly documented at toxic levels: they include all kinds of arrhythmias (sinus node dysfunction is well documented) and QTc prolongation. SA node dysfunction is the characteristic complication of lithium therapy and can manifest clinically as sinus bradycardia or atrioventricular conduction disturbances. Other parameters such as PR and QRS intervals often remain normal. Combining carbamazepine with lithium increases the risk for cardiac arrhythmias.
References:
Lithium is associated with thyroid dysfunction in some cases.
Which of the following is false with respect to this association?
B. Nearly one-fifth of lithium-treated patients show increased plasma thyroid-stimulating hormone (TSH). About 5% show thyroid enlargement (goiter) whereas 5–10% have clinical hypothyroidism. Weight gain and lethargy are the most common clinical features. These effects are dependent on dose and the duration of lithium therapy. Middle-aged women with a preexisting propensity for hypothyroidism in the form of autoantibodies against the thyroid are the most susceptible clinical group.
Compared with the general population, the risk of Ebstein’s anomaly in children of mothers exposed to lithium during the first trimester of pregnancy is:
B. The risk of major congenital anomalies in children exposed to lithium in the uterus is 4–12%. This is nearly three times higher than non-exposed fetuses. The UK National Teratology Information Service has concluded that lithium increases the risk of cardiac malformations by approximately eightfold. First trimester exposure to lithium increases the risk of Ebstein’s anomaly by nearly 10–20 times, bringing the absolute risk to 0.05–0.1%.
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