Question

Your patient arrives in the emergency room with an injury to his head which has damaged his pituitary gland. The damage to his head is affecting most of his organ systems, including the renal system. Hormones from the pituitary are not being secreted.  

1. 1. Because of his head injury, the physician administers mannitol solution to reduce the swelling of his brain. Mannitol is a sugar which appears in the filtrate at the glomerulus but it not recaptured by the body in the rest of the nephron. What effect will the mannitol have on urine formation? Why would the mannitol reduce swelling?  
2. 2. Your patient recovers and the swelling in his brain abates. However, the damage to the pituitary gland persists and the pituitary hormones are absent years later. What sign or symptom RELATED TO ITS ACTION IN THE KIDNEY do you expect to see in your patient that is the result of the lack of this hormone (identified in part a)? Explain briefly. (The question pertains to the urinary system)

Answer 1

a.Mannitol increases the osmotic pressure within the lumen of proximal tubules and loop of henle and causes fractional excretion of the urea,nitogen and sodium.

.Mannitol increases the urine output therefore water doesn't get acccumulated in tissue and prevents swellings.

b. Polyuria (excess urination)and polydipsia (Excessive thirst) can be the sign and symptoms in patient. It occurs due to lack of anti-diuretic hormone ADH and pressor substance release from the posterior lobe of pituitary. ADH functions in increasing the amount of water reabsorption in distal convoluted tubule and collecting duct and causes decreased urin output and plasma osmolarity. Therefore, in this patient condition ,lack of ADH causing less water reabsorption through tubules, thus polyuria.