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Biomedical subjects

C D Hawker

Publications and source records attributed to C D Hawker.

At least 19 recordsLinked to original sources
PubMed1986

Alterations in calcium, phosphorus and C-terminal parathyroid hormone levels in equine acute renal disease.

The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears to have been related to their diminished renal function in that C-terminal fragments of intact PTH (which require functioning kidneys in order to be cleared) were probably being accumulated. Although there was no evidence with regard to an actual increase in PTH secretion, prolongation of intact PTH half-life due to renal tubular damage may have contributed to the development of hypercalcemia.

Acute Kidney Injury↗
PubMed1984

Absence of effect of 24,25-dihydroxycholecalciferol on serum immunoreactive PTH in patients with persistent hyperparathyroidism after renal transplantation.

Three hypercalcemic renal transplant recipients with stable, excellent renal function (creatinine clearance 74 +/- 11.8 ml/min) were treated with 60 micrograms 24,25(OH)2D3 by mouth daily for three months. Immunoreactive c-terminal PTH, intact PTH, 1,25(OH)2D3, 25(OH)D3, 24,25(OH)2D3, and serum and 24 h urine calcium, phosphate, magnesium and creatinine were obtained before, at one week, one month and three months of treatment, and at six weeks post-treatment. Significant elevations in serum levels of 24,25(OH)2D3 were induced by therapy (1.32 +/- .16 ng/ml to 30.06 +/- 5.18 ng/ml at one month). Moderate elevations of c-terminal PTH and normal levels of intact PTH remained unchanged throughout the study. Serum calcium remained elevated, serum phosphate and magnesium remained depressed and creatinine clearance and urinary excretion of calcium, phosphate, and magnesium remained unchanged. Furthermore, 1,25(OH)2D3 and 25(OH)D3 remained in the normal range throughout the study. We conclude that 24,25(OH)2D3 did not have a suppressant effect on levels of iPTH in the clinical setting of persistent hyperparathyroidism after successful renal transplantation.

24,25-Dihydroxyvitamin D 3↗
PubMed1983

Pathogenic mechanisms of the hypocalcemia of the staphylococcal toxic-shock syndrome.

Hypocalcemia is a common finding in TSS. This has been causally related to the hypoalbuminemia of TSS. To more clearly define the mechanism responsible for this hypocalcemia, we examined the serum concentrations of CaT, Ca+ +, iCT, albumin, and DBP in 28 women meeting the case-study definition of TSS. Mean CaT was 2.18 +/- 0.36 mM/L (S.D.), Ca+ + was 0.93 +/- 0.19 mM/L, and iCT was 1941 +/- 978 pg/ml; all were significantly different (p less than 0.01) from the normal values of CaT (2.38 +/- 0.09), Ca+ + (1.09 +/- 0.04) and iCT (less than 30 to 135). A significant inverse correlation was found between iCT and both CaT and Ca+ +, p less than 0.001. Serial values were measured in two women in whom the iCT values declined each day. Gel filtration of the iCT from two patients with the highest values suggested that some polymeric molecular species, rather than authentic CT, accounted for 90% of the circulating iCT value. No abnormalities of DBP levels were found, and no correlation with CaT, Ca+ +, or iCT was evident. The hypocalcemia of the TSS represents a reduction in both CaT and Ca+ + concentrations, which may be at least partially accounted for by the elevated iCT concentrations.

Adolescent↗
PubMed1981

Hormonal responses to high-dose fentanyl anaesthesia. A study in patients undergoing cardiac surgery.

The hormonal responses to anaesthesia and cardiac surgery were studied in 20 patients. Ten patients were anaesthetized with fentanyl 60 microgram kg-1 and nitrous oxide in oxygen and 10 with etomidate 0.3 mgkg-1 and nitrous oxide in oxygen plus halothane. There were no significant changes in cortisol, growth hormone or insulin concentrations in response to surgery in either group, although cortisol concentrations decreased during cardiopulmonary bypass. Both groups showed increases in prolactin concentrations. Patients anaesthetized with etomidate and halothane showed a significant increase in adrenaline and glucose concentrations not seen in the fentanyl group. Cardiopulmonary bypass was associated with marked increases in catecholamines in both groups.

Aged↗
PubMed1980

Prompt resolution of osteomalacia by switching from phenytoin to phenobarbital.

It has been reported that patients taking the anticonvulsant drugs phenytoin and/or phenobarbital may experience osteomalacia. In a phenytoin-treated patient with osteomalacia, switching the drug regimen to phenobarbital led to prompt resolution of her symptoms and restoration of normal serum calcium and serum 25-hydroxyvitamin D values. It seems prudent, when feasible, to switch patients from phenytoin to phenobarbital when their anticonvulsive management is complicated by the onset of osteomalacia. Such simple manipulation of anticonvulsive drug therapy may obviate the need for vitamin D and calcium administration.

Calcium↗
PubMed1980

Parathyroid hormone in chronic renal failure: studies with two different parathyroid hormone radioimmunoassays.

Two assays for immunoreactive parathyroid hormone (iPTH) with different specificities were used to evaluate the role of iPTH measurement in patients with chronic renal failure (CRF). One measured largely C-terminal iPTH fragments, the other largely intact iPTH. In untreated CRF, the log iPRH for each assay was significantly correlated with the reciprocal of the creatinine clearance (CCr). C-terminal iPTH was elevated at relatively high CCr values, but intact iPTH was not elevated until later in the progression of CRF. In hemodialysis patients treated with 25-hydroxyvitamin D3, intct iPTH correlated better than C-terminal iPTH with clinical improvement. These two assays used together were more helpful in evaluation of CRF patients than either assay alone.

Amino Acid Sequence↗
PubMed1976

Acute myeloblastic leukemia and hypercalcemia. A case of probable ectopic parathyroid hormone production.

We studied a patient with acute myeloblastic leukemia, hypercalcemia, hypophosphatemia and inappropriately elevated serum parathyroid hormone levels to define the mechanism of the hypercalcemia. On six occasions during two years, hypercalcemia occurred in conjunction with relapses of leukmia. Each time, serum calcium decreased to normal levels in parallel with reduction of the leukemic mass. During two periods of hypercalcemia, immunoreactive parathyroid hormone values were abnormally high. In addition, hormone was detected in vitro after short-term incubation of the leukemic cells (after 24 hours, the patient's cells produced 129 pg of PTH per milliliter, whereas myeloblasts from a normocalcemic patient with leukemia produced only 33 pg). In freeze-thawing experiments, 39 pg of parathyroid hormone was released form 1 x 108 of the patient's myeloblasts; no hormone was released from the normocalcemia cells. These findings suggest that the hypercalcemia resulted from ectopic parathyroid hormone production by leukemic cells.

Adult↗
PubMed1968

Thyrocalcitonin.

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Biological Assay↗