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Free access

Aliya A Khan, Bart Clarke, Lars Rejnmark and Maria Luisa Brandi

Purpose

Review calcium homeostasis in pregnancy and provide evidence-based best practice recommendations for the management of hypoparathyroidism in pregnancy.

Methods

We searched MEDLINE, EMBASE and Cochrane databases from January 2000 to April 1, 2018. A total of 65 articles were included in the final review.

Conclusions

During pregnancy, calcitriol levels increase by two- to—three-fold resulting in enhanced intestinal calcium absorption. The renal filtered calcium load increases leading to hypercalciuria. PTHrP production by the placenta and breasts increases by three-fold, and this may lower the doses of calcium and calcitriol required during pregnancy in mothers with hypoparathyroidism. The literature however describes a wide variation in the required doses of calcium and calcitriol during pregnancy in hypoparathyroid mothers, with some women requiring higher doses of calcitriol, whereas others require lower doses. Close monitoring is necessary as hypercalcemia in the mother may suppress the fetal parathyroid gland development. Also hypocalcemia in the mother is harmful as it may result in secondary hyperparathyroidism in the fetus. This may be associated with demineralization of the fetal skeleton and the development of intrauterine fractures. Inadequate treatment of hypoparathyroidism may also result in uterine contractions and an increased risk of miscarriage. Treatment targets during pregnancy are to maintain a low normal serum calcium. Calcium, calcitriol and vitamin D supplements are safe during pregnancy. Close monitoring of the mother with a multidisciplinary team is advised for optimal care. If calcium homeostasis is well controlled during pregnancy, most women with hypoparathyroidism have an uncomplicated pregnancy and give birth to healthy babies.

Free access

Francesco Tonelli, Francesco Giudici, Francesca Giusti, Francesca Marini, Luisella Cianferotti, Gabriella Nesi and Maria Luisa Brandi

Objective

Multiple endocrine neoplasia type 4 (MEN4) is an autosomal dominant disorder that presents with a spectrum of clinical manifestations overlapping with those of MEN1 syndrome. It is caused by inactivating mutations of the CDKN1B gene, encoding for p27kip1 cyclin-dependent kinase 2 inhibitor, implicated in cell cycle control. Eight mutations of CDKN1B in MEN4 patients have been published so far. The aim of this study was to characterize the molecular basis of a case of MEN1-like syndrome with a neuroendocrine tumor and persistent primary hyperparathyroidism (PHPT).

Methods

Clinical, biochemical, and genetic evaluation were undertaken in the proband (a 53-year-old Caucasian woman) and in one 34-year-old son. The proband was operated for recurrent PHPT. Sequence analysis of the MEN1 and CDKN1B genes was performed on constitutional and parathyroid tissue DNA. Staining for p27 was carried out in parathyroid tissue.

Results

Neither MEN1 mutations nor large deletions encompassing the MEN1 gene on chromosome 11q13.1 could be detected in the proband. A germline frameshift mutation of CDKN1B (371delCT) was revealed, predicted to generate a truncated p27 (CDKN1B) protein. This mutation was confirmed on somatic DNA from the pathological parathyroid tissue, with the retention of the WT allele.

Conclusions

We report a germline heterozygote frameshift mutation of the CDKN1B gene in a Caucasian woman with a long clinical history of MEN1-like multiple endocrine tumors, along with the finding of the mutation in her son. This is the first report of positive CDKN1B mutation analysis in a male subject and also the first description of recurrent hyperparathyroidism in MEN4.

Restricted access

Annalisa Tanini, Maria Luisa Brandi, Umberto Modigliani, Carlo M. Rotella and Roberto Toccafondi

Abstract. TSH-induced cAMP accumulation in cells obtained from normal and pathological thyroid tissue was studied during the first 12 days of primary culture. In normal thyroid tissue cultures (N = 7), the response of cAMP to TSH was present from the second day of culture and reached its maximum after 8 days. A similar behaviour was observed in cultures obtained from euthyroid sporadic goitres (N = 8), even if the rate of response was slightly lower than that of normal tissue. Similarly, cultured cells from euthyroid 'autonomous' nodules (N = 8) appeared to be responsive to TSH during the period of study, but the rate of response was also lower than in the controls. On the contrary, in cultures obtained from toxic adenomas (N = 5) and from diffuse toxic goitres (N = 5) the response to TSH was absent during the first 4 days of culture. The cells became sensitive to TSH from 6 and 6 day onwards, with the rate of response increasing progressively and reaching its maximum on day 12. Finally, in cultured cells obtained from different areas of multinodular toxic goitres (N = 4), the response to TSH was similar to that of euthyroid goitres in cells prepared from 'cold' areas, and to that of toxic adenomas in cells obtained from 'hot' areas. The present data demonstrate the existence of an inhibitory action of unknown factors, possibly iodothyronines or thyroglobulin, on the TSH effect in short-term cultures obtained from thyrotoxic tissues. A normal TSH responsiveness can be restored when the culture is prolonged.

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Maria Luisa Brandi, Carlo M. Rotella, Annalisa Tanini and Roberto S. Toccafondi

Abstract. In order to investigate the presence of α-adrenergic receptors in human thyroid, we have studied the effect of α-adrenergic agonists and antagonists on cGMP cellular content of human thyroid cells in primary culture. Epinephrine as well as TSH were not able to modify the cGMP cellular levels, while norepinephrine significantly increased cGMP accumulation already at 10 nm, a dose inactive on cAMP accumulation. A non selective α-adrenergic antagonist, phentolamine, significantly inhibited cGMP accumulation induced by norepinephrine. Norepinephrine-induced cGMP accumulation was unaffected by prazosin, an α1-adrenergic antagonist, but was abolished by yohimbine, an α2-adrenergic antagonist. Phenylephrine, an α-adrenergic agonist, produced an increase of cellular cGMP levels without modifying cAMP content. In the presence of TSH, the cGMP response to norepinephrine was not modified; however, the increase of cAMP levels was inhibited by norepinephrine at doses inactive on cAMP accumulation, but active on cGMP levels. The present results demonstrate the existence in human thyroid cells of α2-adrenergic receptors, regulating the guanylate cyclase system. It may be postulated that the counter-regulation exerted by α-adrenergic agonists on the response to TSH operates on the TSH-dependent adenylate cyclase.

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Roberto S. Toccafondi, Maria Luisa Brandi, Carlo M. Rotella and Roberto Zonefrati

Abstract.

Even though adrenergic nerve terminals between and around thyroid follicles and catecholamine stimulation of thyroid adenylate cyclase have been reported, there is no uniform concept on catecholamine interaction with thyrotrophin (TSH) receptors. Therefore, the effect of catecholamines on TSH-stimulated cyclic AMP (cAMP) accumulation in human follicular thyroid cells has been investigated, to thus eliminating the extrathyroidal actions of catecholamines.

Epinephrine, norepinephrine and isoproterenol appeared to be rapid and potent stimulators of intracellular cAMP accumulation, the half maximum increase doses being 4 × 10−7 m, 1 × 10−5 m and 5 × 10−7 m, respectively. While propranolol (1 × 10−5 m) prevented the stimulatory effect of catecholamines and failed to inhibit the effect of bovine TSH, phentolamine (1 × 10−5 m) enhanced the potency of norepinephrine and bovine TSH, leaving that of epinephrine unchanged. The effects of epinephrine (2 × 10−8 m) and isoproterenol (2 × 10−8 m) were additive to that of bovine TSH (0.5 mU/ml), but the effect of simultaneous stimulation with norepinephrine (5 × 10−7 m) and bovine TSH (0.5 mU/ml) was lower than expected. Prenalterol, a selective β1-agonist, did not stimulate cAMP accumulation, while terbutaline, a selective β2-agonist, exerted a potent stimulation. Metoprolol, a selective β1-adrenergic blocker, did not affect the response of thyroid follicular cells to isoproterenol.

These results demonstrate the existence of β-adrenergic receptors in human thyroid follicular cells, mainly of the type β2, apparently not correlated with TSH receptor. The existence of α-adrenergic receptors which counter-regulate TSH functional responses in human thyroid follicular cells is suggested.

Restricted access

Roberto Zonefrati, Maria Luisa Brandi, Carlo M. Rotella, Cesare Selli and Roberto Toccafondi

Abstract.

The biological activity of parathyroid hormone (PTH) has been investigated by measuring intracellular accumulation of cyclic AMP (cAMP) in human kidney cortical cultures. Enzyme dispersed cortical cells from non-invaded kidney poles of patients undergoing nephrectomy for cancer were used after 5 days of primary culture. Bovine PTH (1–84) produced a significant increase of cAMP accumulation in cultured cells at a dose (53.7 ng/ml) 10-fold lower than that found for the minimal stimulatory effect when using preparations of human purified plasma membranes. The action of bovine PTH (1–84) was very rapid, a response was detected after 5 min and a ceiling effect after 30 min. Cortical cells showed a slightly lower sensitivity to synthetic bovine PTH (1–34) (half maximal increase dose: 0.66 μg/ml), compared to bovine PTH (1–84) (half maximal increase dose: 0.32 μg/ml), but revealed a higher sensitivity to human PTH purified from the medium of parathyroid cell cultures (half maximal increase dose: 11.2 ng/ml). Arginine-vasopressin (AVP) also increased the cAMP accumulation of kidney cortical cultured cells, with a potency and efficacy lower than that of human 'culture' PTH, while in kidney medullary cells in primary culture AVP exerted a strong response and the effect of PTH was poor or absent. Calcitonin and glucagon were weak stimulators of kidney cortical cell cAMP accumulation.

Restricted access

Maria Luisa Brandi, Carlo M. Rotella, Andrea Lopponi, Leonard D. Kohn, Salvatore M. Aloj and Roberto Toccafondi

Abstract. Forskolin, at 10−11 m, stimulates guanylate cyclase activity in primary human thyroid cell cultures, but does not modify cAMP accumulation. At a 10-fold higher concentration it still stimulates guanylate cyclase activity and becomes an inhibitor of cAMP production. Above 10−9 m, forskolin stimulation of cGMP decreases, while it also becomes a stimulator of cAMP production. There is an additive effect of TSH and forskolin on cAMP production at concentrations of the diterpene which are stimulatory. Concentrations of forskolin which are inhibitory for cAMP, but stimulatory for cGMP, are inhibitory for TSH stimulation of cAMP. The addition of 8-bromo-cGMP duplicates the forskolin effect at low concentrations.

Restricted access

Maria Luisa Brandi, Carlo M. Rotella, Roberto Zonefrati, Roberto Toccafondi and Salvatore M. Aloj

Abstract. Rat thyroid cells in primary culture augment cAMP production when challenged with β-adrenergic agonists; at 10−5 m the potency is isoproterenol > nor-epinephrine > epinephrine. In analogy with human thyroid cells, rat thyroid primary cultures display α-adrenergic-stimulated cGMP production which inhibits TSH and norepinephrine stimulation of cAMP. Adrenergic regulation of cyclic nucelotide production is lost in the cloned thyroid cell line of rat origin known as FRTL-5. Also the potentiating effect of phentolamine on TSH stimulation of cAMP production in thyroid primary cultures becomes an inhibitory one in the FRTL-5 cells. Neither 'soluble factors' nor contamination of other cell populations could account for the different behaviour of the primary culture and the cell line toward adrenergic regulation. The reported activation by norepinephrine of iodide efflux in FRTL-5 cells rules out the loss of specific adrenergic receptors in the FRTL-5 cells. It is proposed that the cloning of FRTL-5 cells from primary cultures causes an 'alteration' in the coupling of adrenergic receptors to the adenylate cyclase system. This alteration does not affect those mechansism of message transduction that do not involve cAMP as the signal.

Free access

Alberto Falchetti, Alessia Gozzini, Annalisa Terranegra, Laura Soldati, Giuseppe Vezzoli, Gigliola Leoncini, Francesca Giusti, Francesco Franceschelli, Laura Masi, Annalisa Tanini, Loredana Cavalli and Maria Luisa Brandi

Objective

Familial hypocalciuric hypercalcemia (FHH) syndrome is a rare benign condition, inherited as an autosomal dominant trait, in which inactivating mutations of the calcium-sensing receptor (CASR) gene affects the body's ability to regulate calcium homeostasis. Its outcome is featured by increased levels of serum calcium, moderate hypophosphatemia, and inadequately normal or elevated circulating parathyroid hormone levels. Affected patients are mostly asymptomatic and do not benefit from surgical resection of their mildly enlarged parathyroids.

Design

We evaluated for hypercalcemia an Italian family that was identified via a young adult male proband referred to our center for parathyroidectomy.

Methods

The patients and the family members were evaluated both biochemically and genetically as suspected FHH subjects. An in vitro functional study was performed by site-directed mutagenesis, and CASR activity was monitored by measuring intracellular calcium ([Ca2 +]i).

Results

The patient had a novel germline heterozygous CASR mutation (c.361_364GATT; p.D121del/fsX122). The mutation caused a premature stop codon at codon 122, exiting a truncated protein. The biochemical phenotype of all family members carrying the heterozygous deletion was concordant with classic FHH syndrome.

Conclusions

Our findings confirm the role of CASR gene mutational analysis to offer a valuable addition for the recognition of FHH in hypercalcemic patients not yet characterized for a positive familial history of hypercalcemia, the only condition that identifies CASR gene mutations in hypercalcemia.

Open access

Aliya Aziz Khan, Christian Koch, Stanislaus Hendrikus Maria Van Uum, Jean Patrice Baillargeon, Jens Bollerslev, Maria Luisa Brandi, Claudio Marcocci, Lars Rejnmark, Rene Rizzoli, M. Zakarea Shrayyef, Rajesh V Thakker, Bulent O Yildiz and Bart Clarke

Purpose: To provide practice recommendations for the diagnosis and management of hypoparathyroidism in adults

Methods: Key questions pertaining to the diagnosis and management of hypoparathyroidism were addressed following a literature review. We searched PubMed, MEDLINE, EMBASE and Cochrane databases from January 2000 to March 2018 using keywords “hypoparathyroidism, diagnosis, treatment, calcium, PTH, calcidiol, calcitriol, hydrochlorothiazide and pregnancy”. Only English language papers involving humans were included. We excluded letters, reviews and editorials. The quality of evidence was evaluated based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. These standards of care for hypoparathyroidism have been endorsed by the Canadian Society of Endocrinology and Metabolism.

Results: Hypoparathyroidism is a rare disease characterized by hypocalcemia, hyperphosphatemia and a low or inappropriately normal serum parathyroid hormone level (PTH). The majority of cases are post surgical (75%) with nonsurgical causes accounting for the remaining 25% of cases. A careful review is required to determine the etiology of the hypoparathyroidism in individuals with nonsurgical disease. Hypoparathyroidism is associated with significant morbidity and poor quality of life. Treatment requires close monitoring as well as patient education. Conventional therapy with calcium supplements and active vitamin D analogues is effective in improving serum calcium as well as in controlling the symptoms of hypocalcemia.

Parathyroid hormone replacement is of value in lowering the doses of calcium and active vitamin D analogues required and may be of value in lowering long term complications of hypoparathyroidism. This manuscript addresses acute and chronic management of hypoparathyroidism in adults.

Main conclusions; Hypoparathyroidism requires careful evaluation and pharmacologic intervention in order to improve serum calcium and control the symptoms of hypocalcemia. Frequent laboratory monitoring of the biochemical profile and patient education is essential to achieving optimal control of serum calcium.