Disorders of the parathyroid glands

Severe osteogenesis imperfecta caused by CREB3L1 mutation in a cat

We examined the clinical features and pathology, and identified the causative mutation, of osteogenesis imperfecta in a 2-mo-old kitten with growth retardation and abnormal gait. Blood and radiographic examinations were performed on presentation. Radiographs revealed decreased opacity of numerous bones. Fractures were observed in some long bones, including femur and tibia. Histologic examination of the tibia showed decreased osteoid and osteoblasts at the primary spongiosa extending from the growth plate. The periosteum was thickened, and cortical bone and osteoblasts were decreased. Consequently, osteogenesis imperfecta was diagnosed. Genomic DNA and total RNA were extracted from the skin and used for PCR. Whole-genome sequencing identified a 2-bp deletion (c.370_371delTG; p.C124fs), which resulted in a homozygous frameshift mutation on exon 3 of CREB3L1. This mutation introduced a premature stop codon, suggesting production of the truncated protein without a functional domain as a transcription factor for expression of COL1A1 mRNA. This error may have affected collagen fibril formation, leading to the development of osteogenesis imperfecta.

Analytical Validation of a New Immunoenzymatic Method for the Measurement of Feline Parathyroid Hormone in Cats with Chronic Kidney Disease

Simple Summary

Parathyroid hormone (PTH) is involved in many metabolic diseases, such as chronic kidney disease (CKD) and calcium disorders, and its measurement could be of clinical utility. However, available methods for the measurement of feline PTH are limited and not widely accessible. The aim of this study was to perform the analytical validation of a new method for PTH measurement in cats. Thirty-eight cats affected with CKD were included. The analytical protocol provided an evaluation of the precision, accuracy, and storage stability at different temperatures. The method investigated showed good precision and accuracy and good stability for 1 week of storage at freezing temperatures. The method was validated in cats, allowing its future use in diagnostic procedures.

Abstract

The determination of parathyroid hormone (PTH) in cats could be of clinical utility in many metabolic disorders, such as renal diseases, hypercalcemia, or nutritional imbalances. However, the available methods for the measurement of feline PTH are limited, not widely available, and need radioimmunoassays. The aim of this study was to perform the analytical validation of a new immunoenzymatic method for the measurement of feline PTH. Thirty-eight cats affected with chronic kidney disease (CKD) were included. PTH was measured using a two-site immunoenzymatic method validated in humans and dogs (ST AIA-PACK^® Intact PTH, Tosoh Bioscience, Tessenderlo, Belgium). The analytical validation provided the evaluation of precision (intra-assay and inter-assay), accuracy (linearity under dilution (LUD) and spike recovery test (SRT)), and the storage stability of serum samples at 20 °C, 4 °C, and −20 °C. The method showed good precision (intra-assay CVs (coefficient of variations) 3.19–9.61%; inter-assay CVs 9.26–15.28%). In both the intra- and inter-assays, the highest imprecision was found with the low concentration pool (9.61% and 15.28%) and accuracy (LUD and SRT r² = 0.99, p < 0.001), while the stability was optimal up until 7 days at −20 °C (−7.7%). The method was successfully validated in cats, allowing its future use in diagnostic procedures.

Comparison between different sources of minerals in horses with nutritional secondary hyperparathyroidism

ABSTRACT Minerals perform several functions in the body, such as coagulation actions, muscle contraction, enzymatic and hormonal production, among others. This study aims to evaluate the effect of a 150 days chelated and not chelated mineral supplementation with and without potassium oxalate on serological parameters and bone mineral density of horses. Twenty-four crossbred yearlings (12 females and 12 males) with an average age of 21±3 months and body weight of 330.8±37.9kg were divided into four groups containing six equines in each (three females and three males) in a completely randomized design with repeated measurements in a 2x2 factorial arrangement. Treatments were: 1 - chelated minerals compound; 2 - chelated minerals compound and potassium oxalate; 3 - not chelated minerals compound; and 4 - not chelated minerals compound and potassium oxalate. Clinical signs of nutritional secondary hyperparathyroidism (NSH) were observed only in treatment 4. Results showed no treatment effect in bone biopsy for calcium, phosphorus and bone density. There were significant reductions of parathyroid hormone (PTH) means concentrations in treatments 2 and 4 during supplementation. Animals supplemented with chelated minerals compounds avoided mineral imbalances and NSH even when in dietary potassium oxalate challenged.

Primary hyperparathyroidism caused by bilateral parathyroid cystic carcinoma in a cat

Case summary

A 16-year-old neutered female Korat cat presented with chronic vomiting, mild azotaemia and mild hypercalcaemia. Physical examination revealed bilateral palpable masses on each side of the trachea. Laboratory results were consistent with primary hyperparathyroidism, diagnostic imaging findings with cystic thyroid or parathyroid masses, and fine-needle aspiration cytology with thyroid hyperplasia or adenoma. In order to confirm whether one or two of the masses were the cause of the hyperparathyroidism, cystic fluid was aspirated from both for parathyroid hormone concentration measurement. The concentration was shown to exceed that of the serum manyfold in both samples, confirming both masses to be functional and of parathyroid origin. A total parathyroidectomy and thyroidectomy were performed on the right side, and a subtotal thyroidectomy and a subtotal to total parathyroidectomy on the left, without any major postoperative complications. Histopathology was consistent with bilateral parathyroid carcinoma.

Relevance and novel information

To our knowledge, this report is the first to describe a rare case of bilateral parathyroid cystic carcinoma in a cat. It highlights the usefulness of determining parathyroid hormone concentration in the cystic fluid of a suspected neoplastic parathyroid mass preoperatively. It also demonstrates that it may be possible to remove most of the cervical parathyroid and thyroid tissue of a cat without causing any clinically relevant hypocalcaemia or iatrogenic hypothyroidism. However, serum concentrations of ionised calcium, thyroxine and creatinine should be closely monitored in the postoperative period in order to detect and control possible complications.

Pelvic fracture triggering symptoms of an underlying primary hypoparathyroidism in an adult spayed bitch: A case report

A 7-year-old mixed breed spayed bitch (body weight: 10.6 kg) was presented with a history of intermittent episodes of seizures and untreated limb fracture. Appetite loss, nervousness, lateral recumbency, fasciculations, ataxia and poor nutritional condition were found. Venous blood gas analysis highlighted normal acid-base balance and severe low ionized calcium (0.58 mEq/L [range 1.13-1.32 mEq/L]). Marked total hypocalcaemia (6.4 mg/dL [range 8-10] or 1.6 mM [range: 2-2.5]) associated with hyperphosphoraemia (9.3 mg/dl [range 3.5-6.5 mg/dl]) displayed inverted ratio between minerals. ECG showed sinus arrhythmias. Circulating levels of Mg and Cu were within physiological range (1.97 mg/dl and 128 μg/dl respectively) and effects from interactions were excluded. Oral administration of calcitriol at 40 ng/kg/day led to clinical improvement within 48 hours, but circulating iCa levels were still below the lower limit of the reference range. Baseline levels of circulating parathormone (PTH) were 3 pg/ml, along with normal values of circulating vitamin D. Primary hypoparathyroidism was diagnosed as a chronic underlying condition triggered by pelvic fracture.

Dietary supplementation for Santa Inês hair ewes on pasture at pre- and postpartum periods: dry matter intake, digestibility, milk production, and mineral metabolism

The aim of this study was to evaluate the impact of different levels of dietary supplementation and reproductive stages on dry matter intake, digestibility, milk production, and mineral metabolism in Santa Inês hair ewes. Two dietary supplement levels of 0.5 and 1.5%, based on body weight, were used. A total of 12 hair ewes (six subjected to 0.5 and six subjected to 1.5% of concentrate supplementation based on body weight-BW) of the Santa Inês breed were evaluated in a completely randomized design with fixed effects of supplementation level, period, and its interactions. Dry matter intake, digestibility, milk production, and mineral metabolism (calcium (Ca), phosphorus (P), magnesium (Mg), alkaline phosphatase (ALP), type I insulin-like growth factor (IGF-I), parathyroid hormone (PTH), and osteocalcin (OC)) were assessed. Dry matter digestibility was affected by the supplementation level (during both pregnancy and lactation), with higher values in ewes fed at a level of 1.5% of BW. A significant interaction between treatment × reproductive stages was found for the Mg concentration. A period effect (P < 0.05) on serum concentrations of P, Ca/P, Mg, and IGF-I was observed. Serum P concentrations were influenced (P < 0.05) by treatments and reproductive stages. There were significant differences in the Ca/P ratio among the reproductive stages. The enzymatic activity of ALP and serum IGFI differed among reproductive stages. Ewes supplemented at a level of 1.5% of BW produced 18.5% more milk than ewes supplemented at a level of 0.5% of BW. The use of 0.5% of body weight in concentrate supplementation is recommended for the reduction of production costs, without having an effect on the mineral metabolism of Santa Inês hair ewes.

Osteitis fibrosa cystica in a domestic young cat

CASE SUMMARY

A 4-month-old cat had bilateral swellings of the mandible, maxilla, humerus and femur, and angular deviations in the axial and appendicular skeleton. The biochemical profile indicated hypercalcemia, hyperphosphatemia and increased parathyroid hormone levels. Because of the poor prognosis, the cat was euthanized. At necropsy, malleable and fragile bones, associated with numerous cystic areas containing yellowish and translucent liquid, were observed. Histologically, the bones showed marked diffuse proliferation of fibrous connective tissue, and large numbers of osteoclasts surrounding numerous cystic structures were also observed within fibrotic areas at the periphery of the trabecular bone. In addition, enlargement of the parathyroid glands, which was associated with increased serum concentrations of calcium, phosphorus and parathyroid hormone, was detected.

RELEVANCE AND NOVEL INFORMATION

The changes observed in this cat are consistent with hyperparathyroidism-associated osteitis fibrosa cystica, which is an unusual presentation in the cat. Hyperparathyroidism, either primary (neoplastic) or secondary (nutritional or renal), is the primary cause of this condition.

Oral Manifestations of Chronic Kidney Disease and Renal Secondary Hyperparathyroidism: A Comparative Review

Recent epidemiological studies have demonstrated that significant associations exist between oral disease and diseases involving non-oral tissues. Occasionally, the roles may be reversed and the oral cavity can be severely affected by systemic disease originating in another part of the body. Renal secondary hyperparathyroidism is a common endocrinopathy that occurs as a consequence of chronic azotemic kidney disease. Renal osteodystrophy, the most dramatic clinical consequence of renal secondary hyperparathyroidism is uncommon, but can result in demineralization of maxillofacial bones, loosening of teeth, and pathological jaw fractures. The purpose of this report is to update the current understanding of the pathophysiology of this endocrine disease and to compare the oral manifestations of renal secondary hyperparathyroidism in humans and companion animals. A 50-year review of the veterinary literature was undertaken to examine the clinical presentation of renal osteodystrophy in dogs, and to determine what clinical consequences of renal secondary hyperparathyroidism have been reported in domestic cats.

Bone formation controlled by biologically relevant inorganic ions: role and controlled delivery from phosphate-based glasses

The role of metal ions in the body and particularly in the formation, regulation and maintenance of bone is only just starting to be unravelled. The role of some ions, such as zinc, is more clearly understood due to its central importance in proteins. However, a whole spectrum of other ions is known to affect bone formation but the exact mechanism is unclear as the effects can be complex, multifactorial and also subtle. Furthermore, a significant number of studies utilise single doses in cell culture medium, whereas the continual, sustained release of an ion may initiate and mediate a completely different response. We have reviewed the role of the most significant ions that are known to play a role in bone formation, namely calcium, zinc, strontium, magnesium, boron, titanium and also phosphate anions as well as copper and its role in angiogenesis, an important process interlinked with osteogenesis. This review will also examine how delivery systems may offer an alternative way of providing sustained release of these ions which may effect and potentiate a more appropriate and rapid tissue response.

Mechanisms, causes, investigation and management of vomiting disorders in cats: a literature review

Vomiting is a common presenting complaint in feline practice. This article differs from previous reviews in that it is an evidence-based review of the mechanisms, causes, investigation and management of vomiting in the domestic cat. Published evidence was reviewed, and then used to make recommendations for clinical assessment, diagnosis, antiemetic drug treatment, dietary management and monitoring of cats presenting with vomiting. The strength of the evidence on which recommendations are made (and areas where evidence is lacking for cats) has been highlighted throughout.

Reversible myocardial failure in a cat with primary hypoparathyroidism

A 4-year-old domestic shorthair cat presented with tetany. Laboratory testing confirmed severe hypocalcemia and primary hypoparathyroidism. The cat subsequently developed congestive heart failure secondary to myocardial failure and was treated with pimobendan, enalapril, furosemide, calcitriol and calcium salts. All clinical signs resolved and cardiac function returned to normal within 1 month, and remained normal after cessation of all medications except calcitriol. Hypocalcemia-associated cardiomyopathy is a rare, reversible condition that has not previously been reported in a veterinary patient, and it should be considered as a differential diagnosis in patients with myocardial failure.

Feline parathyroid hormone: validation of hormonal assays and dynamics of secretion

Validated assays for quantification of intact parathyroid hormone (I-PTH) are no longer available. Moreover, the third-generation PTH assay that only detects the whole PTH molecule (W-PTH) has never been tested in cats. The work presented here is aimed to validate a commercially available assay for measurement of I-PTH and W-PTH in cats and to study the dynamics of PTH secretion in healthy cats. Our results show that both assays are reliable for the measurement of feline PTH. In healthy adult cats W-PTH concentration (15.1 ± 1.6 pg/mL) was greater (P < 0.001) than I-PTH concentration (9.1 ± 0.7 pg/mL). The dynamics of PTH secretion in response to changes in extracellular calcium (Ca(2+)) were investigated in 13 cats by studying PTH-Ca(2+) curves. PTH-Ca(2+) curves were obtained by intravenous infusion of disodium ethylenediaminetetraacetic acid and CaCl(2). PTH was measured using both I-PTH and W-PTH assays. During hypocalcemia a sigmoidal curve that was similar when measured with I-PTH or W-PTH was obtained. The maximal PTH concentration in response to hypocalcemia was greater with W-PTH (179.6 ± 41.9 pg/mL) than with I-PTH (67.6 ± 10.5 pg/mL; P = 0.01). However, hypercalcemia resulted in an equivalent PTH inhibition, with both assays yielding PTH concentrations as follows: W-PTH = 4.0 ± 0.4 pg/mL and I-PTH = 4.9 ± 0.3 pg/mL (NS). Parameters of the feline PTH-Ca(2+) curve are similar to what has been previously reported in dogs.

Cortisol influence on testicular testosterone secretion in domestic cat: An in vitro study

The aim of the present experiment was to investigate the effect of corticosteroids (exogen) on in vitro testosterone secretion after stress by transportation (40 minutes). Feline testes (Felis silvestris catus) were incubated in the following media: TCM 199; TCM 199 + hCG 10_7M; TCM 199 + hydrocortisone 10_7M, or TCM 199 + hCG + hydrocortisone. The animals (n=21) were allocated into three groups: (S) that arrived at 3 h prior to surgery, (A) that remained in the laboratory for 36 h before being submitted to surgical procedure, and (C) that were also allowed to remain for 36 hours in the laboratory before the surgical procedure, but whose testes had been incubated with hydrocortisone prior to incubation in the referred media. The results showed that group S secreted higher levels of testosterone, regardless of the culture media. It is noteworthy that the suppressing action of hydrocortisone sodium succinate led to a reduction in the testosterone concentration, despite the presence of hCG.

Hiperparatireoidismo em gatos com hipertireoidismo experimental

Os efeitos do hipertireoidismo experimental, 150µg/kg/dia/42 dias de levotiroxina sódica, na homeostase do cálcio foram estudados em 14 gatos sem raça definida, com idades entre um e três anos. A cada 14 dias foram colhidas amostras de soro para a determinação da concentração da tiroxina total (T4), tiroxina livre (FT4), paratormônio intacto (PTH), cálcio total e ionizado, fósforo e, além disso, realizaram-se radiografias para a determinação da densidade mineral óssea (DMO). Observou-se aumento das concentrações séricas do PTH a partir do momento inicial (M0), com diferença significativa deste em relação às concentrações obtidas aos 14 (M1), 28 (M2) e 42 (M3) dias. Não houve diferença significativa nas concentrações séricas de cálcio total e fósforo entre todos os momentos. O cálcio ionizado diminui de M0 para M1 e de M1 para M3, com diferença significativa. Os hormônios tireoidianos apresentaram correlação positiva com o PTH e negativa com o cálcio ionizado. A correlação entre DMO e PTH a partir de M2 foi negativa e entre DMO e fósforo foi negativa somente em M2. Não se observou correlação entre DMO e as demais variáveis. Em M1, M2 e M3 foi observada correlação negativa entre o PTH e o cálcio ionizado. Conclui-se que o hipertireoidismo em gatos adultos jovens está associado ao hiperparatireoidismo secundário devido ao aumento do PTH e diminuição do cálcio ionizado. Os efeitos combinados dos hormônios tireoidianos e do PTH contribuíram para a diminuição da DMO.