Investigating secondary hyperhidrosis.

ing hormone and follicle stimulating hormone with a low oestradiol concentration confirm menopausal status. In peri­ menopause, some menstrual bleeding may still be occurring, and luteinising hormone, follicle stimulating hormone and oestradiol may be normal, or only follicle stimulating hor­ mone may be raised. If there is any doubt about perimeno­ pausal status, blood tests should be repeated in the first few days after the onset of menstrual bleeding, when follicle stimulating hormone is likely to be raised. Thyroid function is an important investigation as hyperthy­ roidism can lead to sweating and to menstrual irregularities with oligomenorrhoea. This should be evident with a low con­ centration of thyroid stimulating hormone in the context of a raised free thyroxine (fT4) or free triiodothyronine (fT3). Full blood count should be done to look for any underlying haematological disorder, in particular a lymphoproliferative or myeloproliferative disorder. Lymphoma is the most com­ mon malignancy associated with night sweats, with around 25% of patients with Hodgkin’s disease experiencing low RATIONAL TESTING Investigating secondary hyperhidrosis