Final answer:
High DHEAS but low FSH and LH in a 4-year-old with precocious puberty symptoms could indicate an adrenal-related condition such as non-classical congenital adrenal hyperplasia or an adrenal tumor, necessitating further diagnostic measures.
Step-by-step explanation:
If a 4-year-old is showing symptoms of precocious puberty with developing adrenarche, and there are high levels of dehydroepiandrosterone sulfate (DHEAS) but low levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), one might be suspicious of a form of non-classical congenital adrenal hyperplasia or an adrenal tumor. Normally, the onset of puberty involves an increase in the production of gonadotropins due to decreased negative feedback sensitivity in the hypothalamus and pituitary. However, in this scenario, elevated DHEAS - an androgen produced by the adrenal glands - with low gonadotropins might suggest an adrenal source of androgens, bypassing the regulatory control exerted by FSH and LH.
This situation can occur when the hypothalamus and pituitary are bypassed or when there is an autonomous production of androgens from the adrenal glands. An adrenal tumor or hyperplasia could produce higher levels of sex steroids independently, leading to the signs of puberty without the typical increase in gonadotropins. Further examinations, including imaging studies and detailed hormonal profiling, are necessary to confirm the diagnosis and establish the appropriate treatment plan.