Biomedical subjects

D Schwarzstein

Publications and source records attributed to D Schwarzstein.

5 recordsLinked to original sources

PubMed1997

Melatonin concentration before and during testosterone replacement in primary hypogonadic men.

OBJECTIVE: To study circadian levels of melatonin in primary hypogonadic adult men before and after testosterone treatment. DESIGN AND METHODS: Circadian serum melatonin profiles were studied in six men with primary hypogonadism before and during testosterone substitution and compared with an age-matched control group (n = 6). RESULTS: Hypogonadal patients had higher plasma melatonin concentrations than the control group during day time (34.2 +/- 8.8 compared with 5.4 +/- 0.5 ng/l, means +/- SD; P < 0.005) and night-time (74.8 +/- 34.5 compared with 30.8 +/- 3.2 ng/l). A 3 months course of testosterone replacement treatment in the hypogonadal group was followed by a diminution of the amplified melatonin circadian rhythm, with lower mean values both during the day (34.2.8 +/- 8 compared with 12.7 +/- 2.45 ng/l, P < 0.001) and at night (74.8 +/- 34.5 compared with 41.5 +/- 13.5 ng/l, P < 0.01), and a decrease in the total area under the curve (958 +/- 318 compared with 475.5 +/- 222.9, P = 0.046). There was a significant negative correlation between melatonin (r = -0.69) and testosterone concentrations. CONCLUSIONS: These data indicate that diminished testosterone in male primary hypogonadism is associated with enhanced plasma levels of melatonin, and that testosterone substitution treatment induces a deamplification of the circadian rhythm of melatonin values in humans.

Adult↗

PubMed1994

[Inadequate TSH secretion. Clinical features, diagnostic criteria, and therapeutic possibilities].

Inadequate secretion of TSH (IST) is a disorder which is diagnosed more frequently and earlier after the introduction of new immunoassay techniques which can distinguish between normal and suppressed TSH levels. For diagnosis high or unsuppressed TSH in required in the presence of elevated levels of the thyroid hormones. Its etiology may be tumor (TSH secreting pituitary adenoma) or non tumoral due to pituitary or generalized resistance to the thyroid hormones. Differential diagnosis between both etiologies is not easy, and several tests have been proposed but are not always discriminatory. Five cases of IST are presented in whom the diagnostic, clinical and therapeutic criteria have been analyzed. The cases of neoplastic IST (patients n.o 3, 4, and 5) showed a loss in circadian rhythm of TSH and absence of suppression with triiodothyronine (T3), 3,5-diiodo 4-(3'-iodine 4'-hydroxyphenoxi) phenylacetic acid (TRIAC) and with bromocriptine. The circadian rhythm of TSH was maintained in the non neoplastic IST (patients n.o 1 and 2) as was suppressed with T3, TRIAC and bromocriptine. The subunit-alpha/TSH quotient and TSH response to TRH were variable with no stimulation being observed with metoclopramide in any case. Upon the demonstration of unsuppressed circulating TSH in the presence of biochemical hyperthyroidism, IST should be suspected to avoid erroneous diagnosis and treatments. Differentiation between neoplastic and non neoplastic origin may be difficult since the biochemical and neuropharmacologic parameters are not always discriminatory.

Adult↗

PubMed1993

Dopaminergic resistance in a case of invasive macroprolactinoma.

Invasive prolactinoma is a relatively infrequent variety of macroprolactinoma characterized by a fast and aggressive growth, with infiltration to adjacent structures, and whose management is frequently difficult. We present the case of a fatal invasive macroprolactinoma in whom resistance to different dopaminergic drugs developed.

Combined Modality Therapy↗

PubMed1992

Outcome and long-term effects of pregnancy in women with hyperprolactinaemia.

Twenty-four women with high circulating prolactin became pregnant on 39 occasions, of which 32 ended in delivery. Sixteen patients showed radiological evidence of pituitary tumour, 6 exhibited a normal CT and 2 had an empty sella. The pregnancies were induced in 4 patients after successful pituitary surgery, in 3 after surgery and medical treatment, and in the rest by bromocriptine (16) long-acting repeatable bromocriptine (1) and methergoline (1). No major complications related to hyperprolactinaemia or its treatment were observed during pregnancy in the patients or offspring. Prolactin after pregnancy was lower than before (basal 95 micrograms/l, after 1st pregnancy 38 micrograms/l P < 0.002, after 2nd pregnancy 24 micrograms/l P < 0.005 compared to basal prolactin); this prolactin reduction tended to be greater in the 9 multiparous patients, but did not attain statistical significance, probably because the number of multiparous patients was too small. A new empty sella developed after delivery in 4 women and persisted in another 2, all of which were medically treated; prolactin fell in all 6 cases normalizing in 3; 4 of these patients had undergone two or more pregnancies. The mean period of follow-up from the last pregnancy was 41.6 months (8-101). These data suggest that pregnancy may hasten a tendency to spontaneous improvement of hyperprolactinaemia, and multiparity may be beneficial in this way.

Adenoma↗

PubMed1992

Computerized tomography versus magnetic resonance imaging: a comparative study in hypothalamic-pituitary and parasellar pathology.

OBJECTIVE: We wished to analyse the relative value of computerized tomography and magnetic resonance in patients referred for evaluation of pituitary and parasellar lesions. DESIGN: We performed a separate evaluation by two independent neuroradiologists of computerized tomography and magnetic resonance images ordered numerically and anonymously, with no clinical data available. PATIENTS: We studied 40 patients submitted for hypothalamic-pituitary study; 31 were carried out preoperatively, of which histological confirmation later became available in 14. The remaining nine patients were evaluated postoperatively. MEASUREMENTS: Over 40 parameters relating to the bony margins, cavernous sinuses, carotid arteries, optic chiasm, suprasellar cisterns, pituitary, pituitary stalk and extension of the lesion were evaluated. These reports were compared with the initial ones offered when the scans were ordered, and with the final diagnosis. RESULTS: Concordance between initial computerized tomography and magnetic resonance was observed in 27 cases (67.5%); among the discordant cases computerized tomography showed the lesion in two, magnetic resonance in 10, while in the remaining case reported to harbour a microadenoma on computerized tomography the differential diagnosis between a true TSH-secreting microadenoma and pituitary resistance to thyroid hormones is still unclear. Both neuroradiologists coincided in their reports in 32 patients (80%); when the initial report was compared with those of the neuroradiologists, concordance was observed with at least one of them in 34 instances (85%). Discordant results were observed principally in microadenomas secreting ACTH or PRL and in delayed puberty. In the eight patients with Cushing's disease (histologically confirmed in six) magnetic resonance was positive in five and computerized tomography in two; the abnormal image correctly identified the side of the lesion at surgery. CONCLUSIONS: In patients referred for evaluation of Cushing's syndrome or hyperprolactinaemia (due to microadenomas) or after surgery, magnetic resonance is clearly preferable to computerized tomography. In macroadenomas both scans are equally diagnostic but magnetic resonance offers more information on pituitary morphology and neighbouring structures. Nevertheless, there are cases in which the results of computerized tomography and magnetic resonance will complement each other, since different parameters are analysed with each examination and discordant results are encountered.

Adenoma↗