- Pulse amplitude and frequency modulation of parathyroid hormone in early postmenopausal women before and on hormone replacement therapy. Harms, H.M., Neubauer, O., Kayser, C., Wüstermann, P.R., Horn, R., Brosa, U., Schlinke, E., Külpmann, W.R., von zur Mühlen, A., Hesch, R.D. J. Clin. Endocrinol. Metab. (1994)