Table 1.

List of conditions associated with CHH or SLDP.

	PARA-PHYSIOLOGICAL CONDITION	DISEASE CONDITION
CLASSIFICATION	SLDP	HYPOGONADOTROPIC HYPOGONADISM
		ORGANIC	FUNCTIONAL
COMMON CAUSES	Common familial component (associated genes: IGSF10, H6ST1, EAP1, LGR4, FTO)	- CHH (Kallmann or CHH, up to 60 genes with variable inheritance and expressivity - CHARGE - MPHD - Acquired lesions (e.g., infiltrative lesions, tumors) - Metabolic diseases (e.g., iron overload) - Autommune diseases (e.g., hypophisitis) - Other genetic syndromes (e.g., Prader-Willi) - Iatrogenic causes (e.g., surgery, radiotherapy)	- Chronic illness - Energy deficit (malnutrition, malabsorption, eating disorder, excessive exercise) - Stress - Drugs (opiates, cannabinoids, dopamine-antagonists and, in males, glucocorticoids) - Other endocrine diseases (e.g., hyper-PRL or male Cushing’s)
		n.b. Hypothalamic amenorrhoea comprosed both energy deficit and genetic elements (Delaney A et al, J Clin Endocrinol Metab. 2021 Mar 8;106(3):e1441-e1452.)
FREQUENCY	1:50	1:5000-20,000