Serum prolactin response to thyrotropin-releasing hormone during status epilepticus

Determination of serum prolactin can help distinguish between epileptic and pseudo-epileptic attacks since generalized tonic-clonic and complex partial seizures frequently are accompanied by a transient rise in prolactin. In status epilepticus, however, serum prolactin levels are well within the normal range: cellular depletion due to the prolonged seizure activity has been suggested as a mechanism for this finding. The control of prolactin secretion is complex. Among several possible regulators, inhibitory dopamine and stimulatory thyrotropin-releasing hormone (TRH) may take part in the regulation of prolactin levels in connection with epileptic activity. There may be subpopulations of prolactin-producing cells that react differently in response to various regulators. A dopamine receptor blocker given during status epilepticus brings forth a distinct increase in prolactin levels. In order to add to the understanding of prolactin changes in connection with status epilepticus, we injected TRH i.v. during status epilepticus in seven consecutive patients. All patients had prolactin levels within the normal range (< 25 micrograms/l) before injection of TRH which resulted in at least a two-fold increase in prolactin levels. Our results contradict the hypothesis of cellular depletion of prolactin in connection with status epilepticus. The mechanism behind prolactin values within the normal range after prolonged seizure activity remains unknown.