This narrated case report illustrates this newly discovered porphyria and also provides some background medical education to the porphyrias as a whole.
almost 9 years ago
The reference given when answering the question about the increase in permeability of sodium ions during hypocalcemia is satisfactory but "does hypocalcemia not reduce the release of neurotransmitters at a chemical synapse" Will it not affect the speed and efficiency of conduction of impulse. Therefore how will it cause tetany?" Reference Increased Permeability of the Sodium Channels When There Is a Deficit of Calcium Ions. The concentration of calcium ions in the extracellular fluid also has a profound effect on the voltage level at which the sodium channels become activated. When there is a deficit of calcium ions, the sodium channels become activated (opened) by very little increase of the membrane potential from its normal, very negative level. Therefore, the nerve fiber becomes highly excitable, sometimes discharging repetitively without provocation rather than remaining in the resting state. In fact, the calcium ion concentration needs to fall only 50 per cent below normal before spontaneous discharge occurs in some peripheral nerves, often causing muscle “tetany.”This is sometimes lethal because of tetanic contraction of the respiratory muscles. The probable way in which calcium ions affect the sodium channels is as follows:These ions appear to bind to the exterior surfaces of the sodium channel protein molecule. The positive charges of these calcium ions in turn alter the electrical state of the channel protein itself, in this way altering the voltage level required to open the sodium gate. From: Guyton, Arthur C. Textbook of medical physiology / Arthur C. Guyton, John E. Hall.—11th ed.
about 8 years ago
I was discussing with a renal consultant the reasons for avoiding thiazides in patients with sarcoidosis with renal involvement. I think it is well established that they can cause hypercalcaemia but after (not very much) searching on the internet and in textbooks I can't seem to find out why? Does anybody know?
over 7 years ago
Researchers at NYU Langone Medical Center and elsewhere say that a vaccination they have developed to fight a brain-based, wasting syndrome among deer and other animals may hold promise on two...
about 6 years ago
Higher overall mortality in men with RLS was independent of known risk factors, and more frequently tied to immune disorders, and respiratory, endocrine, and metabolic diseases.
about 6 years ago
Hypercalcemia is a disorder commonly encountered by primary care physicians. The diagnosis often is made incidentally in asymptomatic patients. Clinical manifestations affect the neuromuscular, gastrointestinal, renal, skeletal, and cardiovascular systems. The most common causes of hypercalcemia are primary hyperparathyroidism and malignancy. Some other important causes of hypercalcemia are medications and familial hypocalciuric hypercalcemia. An initial diagnostic work-up should include measurement of intact parathyroid hormone, and any medications that are likely to be causative should be discontinued. Parathyroid hormone is suppressed in malignancy-associated hypercalcemia and elevated in primary hyperparathyroidism. It is essential to exclude other causes before considering parathyroid surgery, and patients should be referred for parathyroidectomy only if they meet certain criteria. Many patients with primary hyperparathyroidism have a benign course and do not need surgery. Hypercalcemic crisis is a life-threatening emergency. Aggressive intravenous rehydration is the mainstay of management in severe hypercalcemia, and antiresorptive agents, such as calcitonin and bisphosphonates, frequently can alleviate the clinical manifestations of hypercalcemic disorders.
about 6 years ago