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proinflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNFα), and interferon-γ (IFNγ), 9 as well as increased parathyroid hormone (PTH) levels. 10 A recent study 11 in a rodent CKD model with nonregenerative anemia showed the

Open access
in American Journal of Veterinary Research

An increased concentration of plasma PTH is associated with CKD in many species and is known as renal secondary hyperparathyroidism. The prevalence of hyperparathyroidism in cats with azotemic CKD has been reported to be 84%. 1 The primary

Full access
in Journal of the American Veterinary Medical Association

Primary hyperparathyroidism is a disorder of calcium homeostasis. 1–6 The parathyroid gland is responsible for calcium homeostasis. 1–5 In the event of hypocalcemia, the parathyroid gland produces PTH, which acts on the kidneys and intestines

Full access
in Journal of the American Veterinary Medical Association

mineral ions (Ca, P, and Mg), the 2 main calciotropic hormones PTH and CTR are usually quantified in serum for evaluation of mineral metabolism. Parathyroid hormone is a polypeptide secreted by the parathyroid glands that promotes Ca and P release from

Full access
in American Journal of Veterinary Research

Abstract

Objective—To clone and sequence the cDNA for feline preproparathyroid hormone (preproPTH) and to compare that sequence with other known parathyroid hormone (PTH) sequences.

Sample Population—Parathyroid glands from 1 healthy cat.

Procedure—A cDNA library was constructed in λ phage from feline parathyroid gland mRNA and screened with a radiolabeled canine PTH probe. Positive clones were sequenced, and nucleic acid and deduced amino acid sequences were analyzed and compared with known preproPTH and PTH sequences.

Result—Screening of approximately 2 X 105 recombinant plaques revealed 3 that hybridized with the canine PTH probe; 2 clones comprised the complete sequence for feline preproPTH. Feline preproPTH cDNA consisted of a 63-base pair (bp) 5'-untranslated region (UTR), a 348-bp coding region, and a 326-bp 3'-UTR. The coding region encoded a 115-amino acid peptide. Mature feline PTH consisted of 84 amino acids. Amino acid sequence analysis revealed that feline PTH was > 83% identical to canine, bovine, swine, equine, human, and macaque PTH and 69, 71, and 44% identical to mouse, rat, and chicken PTH, respectively. Within the region responsible for hormonal activity (amino acids 1 to 34), feline PTH was > 79% identical to other mammalian PTH sequences and 64% identical to the chicken sequence.

Conclusions and Clinical Relevance—The amino acid sequence of PTH is conserved among mammalian species. Knowledge of the cDNA sequence for feline PTH may be useful to investigate disturbances of calcium metabolism and alterations in PTH expression in cats. (Am J Vet Res 2002;63:194–197)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine effects of exercise on blood ionized calcium (Ca2+) and plasma parathyroid hormone (PTH) concentrations in horses and to compare the effects of exercise-induced and EDTA-induced hypocalcemia on PTH secretion.

Animals

17 horses entered in a show jumping competition and 5 horses given EDTA.

Procedure

Blood Ca2+ and plasma PTH concentrations were measured before and after exercise in the 17 horses entered in the jumping competition. In the other 5 horses, concentrations were measured during infusion of EDTA IV.

Results

Exercise resulted in a significant decrease in blood Ca2+ concentration and a significant increase in plasma PTH concentration, and blood Ca2+ concentration was correlated with plasma PTH concentration. Administration of EDTA resulted in hypocalcemia and an increase in PTH concentration. For the same decrease in Ca2+ concentration, magnitude of the exercise-induced increase in PTH concentration was similar to magnitude of the EDTA-induced increase.

Conclusions and Clinical Relevance

Results suggest that the increase in plasma PTH concentration in horses after exercise is secondary to hypocalcemia and that the increase in PTH concentration seems to be commensurate with the decrease in Ca2+ concentration. (Am J Vet Res 1998;59:1605-1607)

Free access
in American Journal of Veterinary Research

SUMMARY

A radioimmunoassay for measurement of midmolecule parathyroid hormone (pth) concentration in serum from dogs was validated for use on serum from cats. The assay detected an increase in serum concentration of pth after iv infusion of Na2 edta in healthy cats. Infusion of calcium chloride caused a decrease in measured pth. Accuracy of the assay was demonstrated by quantitative recovery of a feline parathyroid gland extract added to pooled feline sera. Mean interassay and intra-assay coefficients of variation were 0.13 and 0.07, respectively. Sensitivity of the assay was 0.1 ng of pth/ml. The median pth concentration measured in 40 adult cats was 3.5 ng/ml, with a range of 1.16 to 11.0 ng/ml.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate changes in plasma ionized calcium (Ca2+) and parathyroid hormone (PTH) concentrations in horses competing in endurance rides.

Design—Longitudinal clinical study.

Animals—28 horses.

Procedure—Venous blood samples were obtained from horses before and after racing 80 km. Plasma pH and concentrations of Ca2+, PTH, inorganic phosphorus, albumin, lactate, and magnesium were measured.

Results—Overall, a significant decrease in mean (± SD) plasma Ca2+ concentration (from 6.44 ± 0.42 to 5.64 ± 0.42 mg/dl) and a significant increase in plasma PTH concentration (from 49.9 ± 30.1 to 148.1 ± 183.0 pg/ml) were found after exercise. Exercise also resulted in significant increases in plasma inorganic phosphorus, albumin, and lactate concentrations. No changes in plasma magnesium concentration or pH were detected after exercise. Plasma PTH concentration was not increased after exercise in 8 horses; in these horses, plasma PTH concentration decreased from 58.2 ± 26.3 to 27.4 ± 22.4 pg/ml, although plasma Ca2+ concentration was also decreased.

Conclusions and Clinical Relevance—Plasma Ca2+ concentration was decreased after racing for 80 km, compared with values obtained before racing. In most horses, an increase in plasma PTH concentration that was commensurate with the decrease in plasma Ca2+ was detected; however, some horses had decreased plasma PTH concentrations. (J Am Vet Med Assoc 2001;219:488–490)

Full access
in Journal of the American Veterinary Medical Association

Summary

The ability of ectopic parathyroid tissue to support calcium homeostasis was evaluated by measuring serum concentrations of calcium, phosphorus, albumin, magnesium, and parathyroid hormone before and for 12 weeks after bilateral thyroparathyroidectomy in 14 cats. During the immediate postoperative period, significant decrease was observed in serum calcium, magnesium, and parathyroid hormone (pth) concentrations. Serum pth concentration remained subnormal and did not significantly increase during the 12-week observation period. Despite persistent hypoparathyroidism, serum calcium and magnesium concentrations gradually increased. Ectopic parathyroid tissue is not capable of maintaining normal serum calcium concentration immediately after thyroparathyroidectomy. Serum calcium concentration gradually normalizes after thyroparathyroidectomy, apparently by means of a pth-independent mechanism.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate calcium balance and parathyroid gland function in healthy horses and horses with enterocolitis and compare results of an immunochemiluminometric assay (ICMA) with those of an immunoradiometric assay (IRMA) for determination of serum intact parathyroid hormone (PTH) concentrations in horses.

Animals—64 horses with enterocolitis and 62 healthy horses.

Procedures—Blood and urine samples were collected for determination of serum total calcium, ionized calcium (Ca2+) and magnesium (Mg2+), phosphorus, BUN, total protein, creatinine, albumin, and PTH concentrations, venous blood gases, and fractional urinary clearance of calcium (FCa) and phosphorus (FP). Serum concentrations of PTH were measured in 40 horses by use of both the IRMA and ICMA.

Results—Most (48/64; 75%) horses with enterocolitis had decreased serum total calcium, Ca2+, and Mg2+ concentrations and increased phosphorus concentrations, compared with healthy horses. Serum PTH concentration was increased in most (36/51; 70.6%) horses with hypocalcemia. In addition, FCa was significantly decreased and FP significantly increased in horses with enterocolitis, compared with healthy horses. Results of ICMA were in agreement with results of IRMA.

Conclusions and Clinical Relevance—Enterocolitis in horses is often associated with hypocalcemia; 79.7% of affected horses had ionized hypocalcemia. Because FCa was low, it is unlikely that renal calcium loss was the cause of hypocalcemia. Serum PTH concentrations varied in horses with enterocolitis and concomitant hypocalcemia. However, we believe low PTH concentration in some hypocalcemic horses may be the result of impaired parathyroid gland function. ( Am J Vet Res 2001;62:938–947)

Full access
in American Journal of Veterinary Research