Childhood Rickets
The causes of rachitic and osteomalacic syndromes are numerous and include a variety of genetic errors, nutritional abnormalities, metabolic disorders, and chronic renal diseases. Quite independent of cause, the clinical…
Clinical Guide to Parathyroid Hormone Assay (Continued)
In summary, the advent of totally automated immunometric I-PTH assays has led to improved accurate clinical discrimination of parathyroid disorders and has provided a tool to measure PTH levels in…
Clinical Guide to Parathyroid Hormone Assay: Different Forms of PTH and Their Detection by Whole (Bioactive) PTH and I-PTH Immunometric Assays
Measurement of biologically active intact PTH is essential for accurate clinical assessment. Today most laboratories use commercially available U.S. Food and Drug Administration (FDA)–approved two sites or sandwich immunometric assays…
Mechanism of Parathyroid Hormone Activity on End Organ: Cyclic AMP Response to PTH
In PHP type 1, cyclic AMP is not synthesized in response to PTH, because of a deficiency of the coupling protein Gαs. As a result, little cyclic AMP is produced…
Mechanism of Parathyroid Hormone Activity on End Organ
PTH produces its effects on target cells by stimulating the synthesis of second messengers, most notably cyclic adenosine monophosphate (cyclic AMP) by the enzyme adenylate cyclase (see Plate 3-9). This…
Pseudohypoparathyroidism
PTH activates its target cells by increasing the activity of adenylyl cyclase, thereby increasing cellular levels of cyclic AMP. Cyclic AMP activates a cascade of proteins that produces the physiologic…
Structure, Physiology, and Pathophysiology of Growth Plate, 40-41
STRUCTURE, BLOOD SUPPLY, AND PHYSIOLOGY The growth plate may be divided into three anatomic components: a cartilaginous component with various histologic zones; a bony component, or metaphysis; and a fibrous…
Clinical Manifestations of Hypocalcemia
More typically, patients with hypocalcemia may be asymptomatic or experience milder symptoms such as muscle cramps and paresthesias. The paresthesias, described as “pins and needles” sensations in the hands, feet,…
Pathologic Physiology of Hypoparathyroidism
Deletions within two nonoverlapping regions of 10p can lead to a phenotype similar to DiGeorge sequence, namely, the hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome. Unlike patients with the…
Clinical Manifestations of Chronic Hypoparathyroidism
Despite the hypocalcemia, soft tissue calcifications may develop in patients with hypoparathyroidism when elevated serum phosphorus levels lead to an elevated (i.e., >70 mg2/dL2) calcium × phosphorus solubility product. A…
