###Human: Is it normal to not get periods even after 16 years of age? ###Assistant: Hello. Prolactin deficiency can cause delayed puberty. Few studies have shown that this delayed puberty is due to prolactin deficiency. Also, check for other possibilities, genetic factors, growth hormone deficiency, etc. In a few cases, supplementation of prolactin may be useful. Please consult your endocrinologist. He will examine and treat you accordingly. Take care.