Hyponatremia may be associated with following thyroid dysfunction
1- Primary hypothyroidism ( rare , and may be related to facilitated ADH function in collecting tubules
2- Secondary hypothyroidism as a part of hypopituitrism and adrenal deficiency.
3- Secondary hyperthyroidism with TSH secretory pituitary tumor with secondary hypopituitarism ( rare ).
Always check full thyroid function and check for adrenal deficiency in all patients with hyponatremia .