Hypoparathyroidism

Risk factors of transient and permanent hypoparathyroidism after thyroidectomy: a systematic review and meta-analysis

BACKGROUND

Postoperative hypoparathyroidism (hypoPT) is a common complication following thyroid surgery. However, current research findings on the risk factors for post-thyroid surgery hypoPT are not entirely consistent, and the same risk factors may have different impacts on transient and permanent hypoPT. Therefore, there is a need for a comprehensive study to summarize and explore the risk factors for both transient and permanent hypoPT after thyroid surgery.

MATERIALS AND METHODS

Two databases (PubMed and Embase) were searched from inception to 2024. The Newcastle-Ottawa Scale was used to rate study quality. Pooled odds ratios were used to calculate the relationship of each risk factor with transient and permanent hypoPT. Subgroup analyses were conducted for hypoPT with different definition-time (6 or 12 months). Publication bias was assessed using Begg's test and Egger's test.

RESULTS

A total of 19 risk factors from the 93 studies were included in the analysis. Among them, sex and parathyroid autotransplantation were the most frequently reported risk factors. Meta-analysis demonstrated that sex (female vs. male), cN stage, central neck dissection, lateral neck dissection, extent of central neck dissection (bilateral vs. unilateral), surgery [total thyroidectomy (TT) vs. lobectomy], surgery type (TT vs. sub-TT), incidental parathyroidectomy, and pathology (cancer vs. benign) were significantly associated with transient and permanent hypoPT. Preoperative calcium and parathyroid autotransplantation were only identified as risk factors for transient hypoPT, while preoperative PTH was a protective factor. Additionally, node metastasis and parathyroid in specimen were associated with permanent hypoPT.

CONCLUSION

The highest risk of hypoPT occurs in female thyroid cancer patients with lymph node metastasis undergoing TT combined with neck dissection. The key to preventing postoperative hypoPT lies in the selection of surgical approach and intraoperative protection.

A case of hypocalcemia-induced dilated cardiomyopathy

Hypocalcemia is a rare cause of dilated cardiomyopathy. Hypocalcemia induced cardiomyopathy is usually reversible when calcium level returns to normal range. We experienced a case of 57-year-old woman who had suffered from hypocalcemia after total thyroidectomy and its consequence of dilated cardiomyopathy. After supplementation of calcium and vitamin D, symptoms of heart failure and LV function were recovered.

Hypocalcemic Heart Failure in Thalassemic Patients

Hypocalcemic cardiomyopathy in primary or secondary hypoparathyroidism is usually refractory to conventional treatment of cardiac failure. We report the case of a thalassemic patient with severe cardiac failure that might have been attributed to several factors, such as hemosiderosis, hypomagnesemia, and hypocalcemia, refractory to conventional cardiac therapy. Cardiac echocardiography showed impaired biventricular performance, and laboratory analyses revealed hypoparathyroidism due to hemosiderosis. When concomitant treatment of heart failure and calcium supplementation was initiated, correction of hypocalcemia resulted in clinical and laboratory improvement, providing strong evidence in support of our hypothesis about hypocalcemic myocardiopathy.

Parathyroid hormone activates PKC-delta and regulates osteoblastic differentiation via a PLC-independent pathway

PTH exerts major effects upon bone by activating PTH/PTHrP receptors (PTH1Rs) expressed on osteoblasts. The PTH1R is capable of engaging multiple signaling pathways in parallel, including Gs/adenylyl cyclase (AC), Gq/phospholipase C/protein kinase C (PLC/PKC) and a distinct mechanism, involving activation of PKC via a PLC-independent pathway, that depends upon ligand determinants within the PTH(29-34) sequence. The involvement of PLC-dependent vs. PLC-independent PKC activation in PTH action was studied in clonal PTH1R-expressing murine calvarial osteoblasts ("Wt9") using two signal-selective analogs, [G1,R19]hPTH(1-28) and [G1,R19]hPTH(1-34). Both analogs lack PLC signaling but differ in their capacity to activate the PLC-independent PKC pathway. Both hPTH(1-34) and [G1,R19]hPTH(1-34), but not [G1,R19]hPTH(1-28), increased differentiation of Wt9 cells during a 16-day alternate-daily treatment protocol. Wt9 cells expressed PKC-betaI, -delta, -epsilon and -zeta, none of which exhibited net translocation to membranes in response to hPTH(1-34) or either analog. hPTH(1-34) induced activation of membrane-associated PKC-delta, however, and a time- and concentration-dependent increase in cytosolic [phospho-Thr505]PKC-delta which was maximal within 40 s at 100 nM in both Wt9 cells and primary osteoblasts. This response was mimicked by [G1,R19]hPTH(1-34) but not by [G1,R19]hPTH(1-28). Increased expression of bone sialoprotein (BSP) and osteocalcin (OC) mRNAs induced by PTH(1-34) and [G1,R19]hPTH(1-34) in Wt9 cells was blocked by rottlerin, a PKC-delta inhibitor. We conclude that PTH1Rs activate PKC-delta by a PLC-independent, PTH(29-34)-dependent mechanism that promotes osteoblastic differentiation.

Primary hypoparathyroidism in two horses

Two Thoroughbred horses were presented with various clinical signs which included sweating, agitation, muscle twitching and synchronous diaphragmatic flutter. These signs were associated with profound hypocalcaemia. A diagnosis of primary hypoparathyroidism was made on the basis of low serum ionised calcium concentration, hyperphosphataemia and markedly reduced serum immunoreactive parathyroid hormone concentrations in the presence of normal renal function. Treatment with a combination of intravenous calcium and subsequently oral calcium, magnesium and a vitamin D analogue (dihydrotachysterol) for up to 65 days resulted in complete remission of clinical signs. Horse 1 was euthanased 12 months after the initial recognition of signs. Results of necropsy were unremarkable apart from an absence of detectable parathyroid tissue. Horse 2 returned to athletic activities while receiving only maintenance doses of oral calcium carbonate.

Hypoparathyroidism--a long-term follow-up experience with 1 alpha-vitamin D3 therapy

OBJECTIVE

Previous studies have suggested that alpha-D3 therapy can cause deterioration in renal function. We have, therefore, examined the long-term effect of 1 alpha-hydroxyvitamin D3 (alpha-D3) administration upon renal function in hypoparathyroid patients.

DESIGN

This is a prospective long-term follow-up study of alpha-D3 administration on hypoparathyroid patients at a mean daily dose of 1 microgram (range 0.5-2.5 micrograms) during a total of 2040 patient-months.

PATIENTS

Seventeen unselected patients (14 females and 3 males), two with primary and 15 with post-surgical hypoparathyroidism.

RESULTS

The significant effect of alpha-D3 on serum and urinary calcium was achieved during the first week of treatment and remained stable at the same range during the close follow-up of 2040 patient-months. No significant change was observed in the serum creatinine during the whole follow-up period. During follow-up, five women developed hypercalciuria and one patient developed hypercalcaemia that disappeared when the dose of the drug was reduced or discontinued.

CONCLUSIONS

From our study we concluded that alpha-D3 is a safe and effective drug in the long-term therapy of hypoparathyroid patients.

Calcium metabolism

In normal individuals, 1,25-dihydroxyvitamin D (1,25-D) levels regulate calcium (Ca) absorption according to Ca intake; its synthesis is stimulated by low Ca intake, probably via increased parathyroid hormone (PTH) secretion, to increase Ca absorption, and suppressed during high intake to reduce Ca absorption. The body also adapts Ca absorption in response to renal Ca excretion, and phosphate absorption in response to phosphate intake. These adaptations may fail or be impaired in certain diseases. In disorders of overadaptation, the intestinal tract absorbs excessive amounts of Ca due to overproduction of 1,25-D, as in absorptive hypercalciuria, sarcoidosis, primary hyperparathyroidism, and tumoral calcinosis. Intestinal hyperabsorption and hypercalciuria may occur on both low- and high-Ca diets. Primary hyperparathyroidism and hypoparathyroidism are bihormonal, related to over- and underproduction, respectively, of both 1,25-D and PTH. Underadaptation disorders are typically related to low 1,25-D synthesis or resistance to this metabolite; examples include postmenopausal osteoporosis, chronic renal failure, and osteomalacia. Many of these adaptational disorders can be relieved or improved by manipulating Ca, phosphate, sodium, or protein intake or by administering exogenous 1,25-D. Overabsorption of Ca and other substances, such as oxalate, may be responsible for Ca nephrolithiasis. Hypocitraturia (which may be a complication of certain diseases or the result of unbalanced diet or excessive exercise), diets high in readily metabolizable sugars and purine-rich proteins (meat, poultry, and fish), and low fluid intake can all contribute to stone formation. Various regimens may reduce the risk of Ca nephrolithiasis.

Pseudohypoparathyroidism: current concepts

Following a brief discussion of the diagnosis and classification of hypoparathyroidism, this review will focus on current concepts of pseudohypoparathyroidism. Topics to be covered will include differing resistance of kidney and bone to parathyroid hormone, relationship of estrogen and pregnancy to Ca homeostasis, normocalcemic pseudohypoparathyroidism, and current understanding of pathogenesis based on various defects in the hormone receptor-adenylate cyclase system. Evidence for physiologic derangements beyond the impaired generation of cyclic AMP will be reviewed, as well as involvement of nonendocrine systems by the deficiency of the stimulatory guanine nucleotide connecting protein. Finally, semantic confusion resulting from the faulty term "pseudopseudohypoparathyroidism" will be addressed.

Spontaneous hypoparathyroidism: clinical, biochemical and radiological features

The clinical, biochemical and radiological features of spontaneously occurring hypoparathyroidism in 13 patients (mean age 9 years, range 4 months to 20 years) are highlighted. Nine patients presented with a history of generalised seizures and 2 were in acute hypocalcemic crisis at the time of admission. Ocular involvement (corneal opacities, cataract) was present in 3 patients and vitiligo in 1 patient. The serum calcium level was low (mean 5.46 mg/dl, range 5.0-7.2) and serum phosphorus level was high (mean 8.49 mg/dl, range 6-14 mg/dl) in all the patients. Six patients had elevated serum alkaline phosphatase (greater than 20 KAU). Radiological examination revealed osteopenia in 3 patients. Nine patients underwent a head CT scan; 5 had evidence of basal ganglia calcification. The findings of elevated serum alkaline phosphatase and osteopenia are at variance with existing literature and may possibly reflect pre-existing vitamin D deficiency.

Familial hypoparathyroidism due to an abnormal parathyroid hormone molecule

The case of a 53-year-old man with familial hypoparathyroidism in the presence of circulating immunoreactive PTH is discussed. The patient responded to exogenous PTH by an increase in urinary cAMP excretion and by several post cyclase parameters including an increase in serum calcium and 1,25-dihydroxyvitamin D, an increase in urinary phosphate excretion and a decrease in urinary calcium. Immunoreactive PTH was detected in this patient's serum by three separate anti-PTH antisera. This immunoreactive PTH behaved aberrantly with these antisera. Nonparallelism to the standard curve was seen in two radioimmunoassays and the material was detected by an antiserum which preferentially binds bovine PTH. No circulating PTH binding activity was detectable. Family studies confirmed the genetic nature of the abnormality. HPLC studies revealed the presence of an abnormally hydrophobic fraction containing immunoreactive PTH. We believe these findings constitute strong evidence for the presence of an abnormal PTH molecule with reduced biological activity resulting in hypoparathyroidism.

Endocrine control and disturbances of calcium and phosphate metabolism in children

Most disorders of extracellular calcium and phosphate metabolism in childhood can be attributed to primary increased or decreased secretion/action of 1,25-dihydroxyvitamin D3 and parathyroid hormone or primary increased or decreased urinary excretion of phosphate and calcium. Based on this pathogenetic classification the most important diseases related to calcium and phosphate metabolism will be discussed.

Calcium deficiency and supraorbital headache: a clinical study of adult subjects

The present study was aimed at investigating the relationship between "chronic constitutional tetany" (spasmophilia) and headache. Several adult patients presenting with neuromuscular hyperexcitability, anxiety, dysautonomia, and oculofrontal headache were subjected to a series of ion and hormone blood tests, and the results were compared with those in control subjects. Calcium and parathyroid hormone levels were significantly decreased, and phosphorus and beta-endorphin-like immunoreactivity were significantly increased. A subgroup of the patients had all four abnormalities. In most cases the family history was positive for headache. Sleep disturbances and personal histories of periodic syndrome in infancy were recorded. It is concluded that a correlation may exist between the symptoms assessed and an impairment of some ion and hormone levels. There are several traits in common with "common migraine", and our patients may form a subgroup of that group. A possible linkage between headache/tetany and the periodic and hyperventilation syndromes is discussed. The increased beta-endorphin-like immunoreactivity is putatively a reactive phenomenon.

Ectodermal defects and chronic mucocutaneous candidiasis in idiopathic hypoparathyroidism

Idiopathic hypoparathyroidism is a rare disorder produced by parathyroid hormone deficiency of unknown cause. It is often associated with other endocrine abnormalities. Patients with idiopathic hypoparathyroidism frequently develop ectodermal disease, including dry, rough skin: coarse, brittle hair; and lusterless, distally split nails. All of these complaints are relatively common in a dermatologic practice. Chronic mucocutaneous candidiasis is also a manifestation of idiopathic hypoparathyroidism. A patient is presented with a prominent ectodermal dysplasia and a chronic mucocutaneous candidiasis that were due to the underlying idiopathic hypoparathyroidism. A brief review of idiopathic hypoparathyroidism is included, as well as the implications of this diagnosis in terms of differential diagnosis, associated endocrine disorders, and therapy.

Pre-menstrual syndrome--are gonadotropins the cause of the condition?

It is proposed that premenstrual syndrome results from the action of elevated gonadotropin levels in various tissues of body other than their natural target organs. These levels are derived from an increased sensitivity to estrogen after pregnancy, childbirth, etc., particularly with respect to the positive feedback on gonadotropin release from the pituitary. Estrogen in conjunction with gonadotropin-releasing hormone (GnRH) releases excessive amounts of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) at ovulation and in the premenstrual phase (post-menopausal patients have greatly elevated gonadotropins and can also demonstrate cyclic symptoms). Gonadotropin action via adenylate cyclase in the adrenal cortex elevates cortisol, while antagonism of parathyroid hormone action on bone gives rise to hypocalcemia. The physiological and psychological symptoms may thereby be explained.

Effects of 1,25 dihydroxyvitamin D3 administration on circadian mineral rhythms in humans

1,25 Dihydroxyvitamin D3 (1,25(OH)2D3) (2.0 micrograms) was given intramuscularly to 6 healthy adult males. Twenty-four circadian patterns of blood-ionized calcium (Ca2+), serum phosphate (Pi), and total calcium (CaT) were assessed pre- and posthormone administration. Correlations of mean mineral rhythms with normative models were significant for each mineral pattern on both study days. Mean Ca2+ and CaT rhythms became weakly correlated after hormone treatment (r = .39). A small but statistically significant increment in the 24 h grand mean Ca2+ concentration was observed on the treatment day compared with the baseline day. However, this increment is less than the year-to-year variability in the grand mean mineral concentrations derived from the same subjects studied under baseline conditions previously. These data indicate that acute parenteral administration of near-physiological (2.0 micrograms) doses of 1,25(OH)2D3 appears to have no major effect on circadian mineral pattern shape or mean mineral concentrations.

Hypocalcemic heart failure

Hypocalcemia is a relatively uncommon but reversible cause of congestive heart failure. A 39-year-old woman with hypocalcemia due to untreated hypoparathyroidism presented with congestive heart failure and a left ventricular ejection fraction of 25 percent. She had no evidence of underlying cardiac disease. The serum calcium level was normalized within one week, associated with complete clearing of the signs and symptoms of heart failure and a twofold increase to 50 percent in the ejection fraction. This is the first patient without underlying myocardial disease in whom significant improvement of left ventricular function has been quantitatively assessed prior to and following correction of hypocalcemia.

Renal handling of calcium in hypoparathyroidism

Treatment of hypoparathyroidism usually requires the use of pharmacological doses of parent vitamin D or near physiological amounts of the hydroxylated metabolites, calcitriol or alphacalcidol. Vitamin D intoxication and hypercalcaemia may be a problem but can be minimised by the use of small doses of vitamin D or its metabolites combined with large amounts of oral calcium. The response to treatment can be easily monitored by measuring serum and urinary calcium and creatinine concentrations. This allows the derivation of two simple indices reflecting calcium load presented to the kidney (calcium excretion in mmol/l glomerular filtrate) and renal tubular calcium reabsorption (TmCa/GFR). These can be used to predict the requirement of calcium supplements and also identify those patients at particular risk of hypercalcaemia.

Pseudohypoparathyroidism and hypocalcemic "myopathy". A case report

A patient with the clinical features of pseudohypoparathyroidism and elevated concentrations of serum CK and LDH, which normalized after successful therapy, is described. Clinical signs of myopathy did not exist. The bioptical material from the m. tibialis anterior was microscopically normal. The biochemical analysis revealed a reduced phosphorylase-a-activity with the total phosphorylase-activity (a and b) being within the normal range. The significance of these findings as well as possible pathogenetic mechanisms are discussed.