Which hormone deficiency leads to excessive urination and dehydration?
A deficiency of vasopressin (ADH) leads to diabetes insipidus, causing excessive urination and dehydration. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Human Physiology - Digestion, Respiration, Circulation, Neural Control and Chemical Coordination, Topic: Organ system functions and hormonal regulation.