Central diabetes insipidus is characterised by-
Central diabetes insipidus is characterised by deficient production of ADH by the hypothalamus. In pituitary, gestational, or nephrogenic DI, there is polyuria (5-20 L or more in 24 hrs)and the urine is of low specific gravity and osmolality. The polyuria results in a small (1-2%) decrease in body water and a commensurate increase in plasma osmolarity and sodium that stimulates thirst and a compensatory increase in water intake. Thus in diabetes insipidus there is low osmolality of urine (below 600 mOsm/kg) in the presence of high plasma osmolality (greater than 300 mOsm/kg). The most common d/d is primary polydipsia where the urine is excessively dilute with low plasma osmolality. Reference : page 794 Davidson's Principles and practice of Medicine 22nd edition
Low plasma and low urine osmolality
High plasma and high urine osmolality
Low plasma and high urine osmolality
Low urine and high plasma osmolality
Endocrinology