RESUMO
Primary adrenal insufficiency secondary to syphilis is extremely rare, with only five cases being reported in the literature. We report a case of adrenal insufficiency as a manifestation of Treponema pallidum infection (tertiary syphilis). A 69-year-old, previously fit and well Caucasian male was found to have adrenal insufficiency after being admitted with weight loss, anorexia and postural dizziness resulting in a fall. Biochemical testing showed hyponatraemia, hyperkalaemia, and an inadequate response to Synacthen testing, with a peak cortisol level of 302 nmol/L after administration of 250 µg Synacthen. Abdominal imaging revealed bilateral adrenal hyperplasia with inguinal and retroperitoneal lymphadenopathy. He was started on hydrocortisone replacement; however, it was not until he re-attended ophthalmology with a red eye and visual loss 1 month later, that further work-up revealed the diagnosis of tertiary syphilis. Following a course of penicillin, repeat imaging 5 months later showed resolution of the abnormal radiological appearances. However, adrenal function has not recovered and 3 years following initial presentation, the patient remains on both glucocorticoid and mineralocorticoid replacement. In conclusion, this case highlights the importance of considering syphilis as a potential differential diagnosis in patients presenting with adrenal insufficiency and bilateral adrenal masses, given the recent re-emergence of this condition. The relative ease of treating infectious causes of adrenal lesions makes accurate and timely diagnosis crucial. LEARNING POINTS: Infectious causes, including syphilis, should be excluded before considering adrenalectomy or biopsy for any patient presenting with an adrenal mass.It is important to perform a full infection screen including tests for human immunodeficiency virus, other blood-borne viruses and concurrent sexually transmitted diseases in patients presenting with bilateral adrenal hyperplasia with primary adrenal insufficiency.Awareness of syphilis as a potential differential diagnosis is important, as it not only has a wide range of clinical presentations, but its prevalence has been increasing in recent times.
RESUMO
The various hypothalamic-pituitary-end-organ/gland axes are central to the regulation of mammalian homeostasis. These have a core role in integrating the response of both endocrine and nervous systems to external and internal stimuli, by means of multi-level signalling through negative and positive feedback loops. The content of these hormonal signals is overwhelmingly conveyed in a rhythmic secretory pattern (frequency modulation of signal) that is energetically more efficient in transmitting neuroendocrine signals than the alternatives (modulation of signal by amplitude or by total area-under-curve). These rhythmic neuroendocrine secretions are individually distinct but the majority display a common feature of low-level basal secretion with superimposed pulsatile rhythms. The underlying mechanisms contributing to this unique rhythmic secretion are complicated and incompletely understood, but are beginning to be better defined as a result of several elegant studies performed in recent years. In some cases, signal transduction in the target tissue is critically dependent upon a pulsatile input, but in others the observed pulsatility is a downstream echo of obligate pulsatility exhibited by a higher-level control hormone. Thus, the gonads are presented with a pulsatile gonadotrophin signal, not because this is essential to gonadotrophin action (the same level of stimulation can be elicited by a continuous input), but as a downstream consequence of pulsatile GnRH-mediated stimulation of pituitary gonadotrophs. By contrast, rhythmicity of signal is embedded at all levels of the hypothalamo-pituitary-adrenal axis. Hypothalamic-pituitary rhythmic secretions are influenced by various internal and external inputs such as age, gender, sleep and wakefulness, food intake, light (photoperiod) or exposure to stress. Understanding the physiological significance of the rhythmic secretion of hypothalamic and pituitary hormones has the potential to provide insights into disease mechanisms, to validate diagnostic tests and, ultimately, to help develop novel therapeutic interventions. This chapter will overview the physiological basis of rhythmic secretion of hypothalamic and pituitary hormones, principally in humans and, by reference to specific examples, describe the various feedback loops and internal and external stimuli that precisely determine these neuroendocrine secretory patterns.
