Fibroblast growth factor-23 (FGF23) is produced in osteoblasts (from bone) in response to increases in serum phosphate (Pi). It binds to the fibroblast growth factor receptor of the parathyroid and suppresses PTH release. This may seem contradictory because PTH actually helps rid the blood of phosphates but it is also causes release of phosphate into the blood from bone resorption. FGF23 inhibits PTH and then takes its place helping inhibit re-absorption of phosphate in the kidney without the phosphate releasing effect on bones. Disorders
Hyperparathyroidism, the presence of excessive amounts of parathyroid hormone in the blood, occurs in two very distinct sets of circumstances. Primary hyperparathyroidism is due to autonomous, abnormal hypersecretion of PTH from the parathyroid gland, while secondary hyperparathyroidism is an appropriately high PTH level seen as a physiological response to hypocalcemia. A low level of PTH in the blood is known as  hypoparathyroidism and is most commonly due to damage to or removal of parathyroid glands during thyroid surgery. There are a number of rare but well-described genetic conditions affecting parathyroid hormone metabolism, including pseudohypoparathyroidism, familial hypocalciuric hypercalcemia, and autosomal dominant hypercalciuric hypocalcemia. Of note, PTH is unchanged in pseudopseudohypoparathyroidism. In osteoporotic women, administration of an exogenous parathyroid hormone analogue (teriparatide, by daily injection) superimposed on estrogen therapy produced increases in bone mass and reduced vertebral and nonvertebral fractures by 45 to 65%. Measurement
PTH can be measured in the blood in several different forms: intact PTH; N-terminal PTH; mid-molecule PTH, and C-terminal PTH, and different tests are used in different clinical situations.
Fibrolamellar hepatocellular carcinoma (FHCC) is a rare form of hepatocellular carcinoma (HCC) that typically affects young adults and is characterized, under the microscope, by laminated fibrous layers interspersed between the tumour cells. Approximately 200 new cases are diagnosed worldwide each year. Cause
A recent study showed the presence of the DNAJB1-PRKACA chimeric transcript (resulting from a 400kb somatic deletion on chromosome 19) in 100% of the FHCCs examined (15/15) This gene fusion has been confirmed in a second study. Pathology
The histopathology of FHCC is characterized by laminated fibrous layers, interspersed between the tumor cells. Cytologically, the tumor cells have a low nuclear to cytoplasmic ratio with abundant eosinophilic cytoplasm. Tumors are non-encapsulated, but well circumscribed, when compared to conventional HCC (which typically has an invasive border). Diagnosis
Due to lack of symptoms, until the tumor is sizable, this form of cancer is often advanced when diagnosed. Symptoms include vague abdominal pain, nausea, abdominal fullness, malaise and weight loss. They may also include a palpable liver mass. Other presentations include jaundice, ascites, fulminant liver failure, encephalopathy, gynecomastia (males only), thrombophlebitis of the lower limbs, recurrent deep vein thrombosis, anemia and hypoglycemia.The usual markers for liver disease – aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase – are often normal or only slightly elevated. FHCC often does not produce alpha fetoprotein (AFP), a widely used marker for conventional hepatocellular carcinoma.