Growth hormone and prolactin secretion in liver cirrhosis: evidence for dopaminergic dysfunction

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Abstract
Increased serum growth hormone (GH) and prolactin (Prl) levels and abnormal responses to some stimuli have been reported in patients with chronic liver disease. Serum GH and Prl concentrations were measured in 11 cirrhotic patients and in sex and age matched healthy controls in basal conditions and after administration of L-dopa alone (500 mg), and L-dopa (100 mg) with carbidopa (35 mg) following pre-treatment with carbidopa (50 mg every 6 h for 1 day), a regimen which results in selective activation of brain dopaminergic pathways. Basal GH and Prl levels were significantly higher in cirrhotics than in controls; serum GH did not increase significantly and serum Prl was subnormally inhibited in patients after both tests. A patient with clearcut hyperprolactinemia unresponsive to dopaminergic stimulation showed normal basal Prl levels and suppression by L-dopa following clinical improvement, while her elevated GH levels remained unchanged and did not increase after L-dopa. These data confirm the existence of abnormalities in the regulation of GH and Prl release in liver cirrhosis and suggest that dopaminergic dysfunction may be responsible. The subnormal Prl suppression induced by L-dopa, which stimulates both brain and peripheral dopaminergic receptors, suggests that dopaminergic dysfunction is not confined to the CNS in liver cirrhosis. Serum Prl concentration may be of value in monitoring decompensated liver disease and abnormalities of Prl secretion may be reversible with clinical improvement.