Question

In patients with chronic kidney disease the alterations of the endocrine system may arise from several causes. The kidney is the site of degradation as well as synthesis of many different hormones. Moreover, a number of pathological conditions can occur. Using what you have learned and read so far along with a little research name one condition or issue that could arise in a CKD patient involving the Endocrine System. (400 words).

Answer 1

Secondary hyperparathyroidism:

Secondary hyperparathyroidism (SHPT) is common in patient with chronic kidney disease (CKD)..It occurs when the parathyroid glands become enlarged and release too much parathyroid hormone, causing high blood level of PTH..There are some reason why it is happening in patient with kidney disease..The reason is due to high blood phosphorus level,kidneys can not make active vitamin D,lower blood calcium level..

Secondary parathyroidism can cause bone disease..It also cause high calcium buildup in tissues and organs like heart and blood vessels..High PTH levels can lead to

- weakening of the bones

- calciphylaxis( skin ulcer and death of surrounding tissue)

- cardio vascular complications

- abnormal fat and sugar metabolism

- itching

- low blood count ( anemia)

Early diagnosis of secondary hyperparathyroidism is crucial in the management of patients with CKD.. Treatment involves contribution of dietary phosphorus restrictions, phosphate binders, vitamin D analogue and calcimimetics.

PTH is the most important regulator of calcium metabolism..It is a polypeptide contain 84 amino acids and secreted by the chief cells of the parathyroid glands in response to hypocalcemia and hyperphosphatemia. PTH acts in 2 organs that is bone and the kidney.PTH stimulates the 1-alpha hydroxylase activity in the kidney,it increases in 1,25 dihydroxyvitamin D production..It also increase the reabsorption of calcium in the distal renal tubules, decreasing calcium clearance..PTH can reduce the reabsorption of phosphorus in the proximal renal tubules from 85% in healthy individuals to less than 15% in dialysis patients..Along with PTH,vitamin D needed for bone reabsorption of urinary calcium and phosphorus in the renal tubules.

Recent studies showed fibroblasts growth factor (FGF)-23 as a new protein with phosphatic activity..It secreted by osteocytes and important factors for regulation of phosphorus homostasis..FGF-23 inhibits the 1,25 dihydroxyvitamin D level.. when GFR falls below 30 ml/ min in case of CKD stage IV the tubular reabsorption of phosphorus can not be further lowered,causing more PTH and FGF-23 secretion..PTH is no more active on the kidney..so high phosphorus causes PTH secretion and PTH causes more hyperphosphatemia..

Management:

Secondary hyperparathyroidism started at the beginning of CKD stage III..it is a complex process.. Treatment goal vary as per CKD stages..serum calcium,phosphorus,PTH levels should be measured in all kidney disease and estimated GFR <60ml/ min..diet restrictions in phosphorus level, vitamin D derivation, calcimimetics and even parathyroidectomy is a final treatment for secondary hyperparathyroidism with CKD..