Comment

Clinical update: sporadic primary hyperparathyroidism

Some patients with primary hyperparathyroidism (PHPT) have an elevated PTH that does not always correlate with high blood calcium levels. We aimed to compare the clinical presentation between normocalcaemic and hypercalcaemic forms using ionized calcium levels as an inclusion criterion.

We included all patients referred for surgery for PHPT between January 2015 and December 2017. Patients were divided into 2 groups (hypercalcaemic (hPHTP)/normocalcaemic (nPHPT)).

104 patients were included.64% of the patients who were initially classified as normocalcaemic had high ionized calcium levels. There were no differences between groups except in terms of bone resorption parameters:patients with hypercalcaemia had higher osteocalcin (37.4vs23.5 ng/mL,P = .02), collagen amino-terminal propeptide (73.5vs49.2 ng/mL,P = .005), and beta-CTX levels (0.68vs0.38 ng/mL,P = .001). Bone involvement as measured by densitometry was similar.

When these patients’ diagnosis and classification is accurate, their clinical presentation and symptoms are similar to those of the classical form. Since the only difference is in terms of bone resorption parameters, in most cases it seems to be an attenuated form or even similar to the classical presentation. The improvement in diagnostic sensitivity supports the use of ionized calcium levels in patients suspected to have nPHPT.

Disorders of mineral metabolism may cause neurologic manifestations of the central and peripheral nervous systems. This is because plasma calcium stabilizes excitable membranes in the nerve and muscle tissue, magnesium is predominantly intracellular and is required for activation of many intracellular enzymes, and extracellular magnesium affects synaptic transmission. This chapter reviews abnormalities in electrolytes and minerals which can be associated with several neuromuscular symptoms including neuromuscular irritability, mental status changes, cardiac and smooth muscle changes, etc.

La gammagrafía con tecnecio-sestamibi (MIBI) es la prueba de elección para la localización de los adenomas en pacientes con hiperparatiroidismo primario (HPTP). En algunos estudios se ha sugerido que el aumento de la sensibilidad de esta prueba podría estar en relación con una disminución de la captación del radiotrazador por parte de la glándula tiroidea. El objetivo de este estudio es analizar nuestra experiencia en pacientes con gammagrafías con MIBI negativas en los que se repitió el estudio tras la supresión de la función tiroidea con tiroxina.

Entre enero de 2006 y abril de 2011 se evaluaron de forma prospectiva 17 pacientes con HPTP e imagen gammagráfica con MIBI negativa en los que se repitió dicha prueba tras la administración de tiroxina. Se revisan los datos gammagráficos y la correlación con los hallazgos en la intervención quirúrgica.

La media de TSH en el momento de repetir la MIBI fue de 0,12 + 0,1 mlU/L. De los 17 pacientes incluidos, en 13 de ellos (76,5%) la gammagrafía bajo supresión de la función tiroidea fue positiva, y en los otros 4 pacientes (23,5%) no se encontró imagen sugestiva de adenoma. En los casos en los que el MIBI fue positivo tras la supresión, el valor predictivo positivo (VPP) fue del 100%.

La supresión de la función tiroidea mediante la administración de tiroxina puede ayudar a mejorar la sensibilidad del MIBI en pacientes con estudios gammagráficos previos negativos y ayudar a tratar de una forma mínimamente invasiva a pacientes con HPTP.

Scintigraphy with technetium-sestamibi (MIBI) is the test of choice for localising adenomas in patients with primary hyperparathyroidism (PHPT). In some studies it has emerged that the increase in sensitivity of this test could be associated with a decrease in the uptake of the radiotracer by the thyroid gland. The aim of this study is to analyse our experience in patients with a negative scintigraphy with MIBI, and in whom the study was repeated after suppression of thyroid function with thyroxine.

A prospective evaluation was performed on 17 patients who, between January 2006 and April 2011, had PHPT and negative imaging using scintigraphy with MIBI and who had the test repeated after the administration of thyroxine. The scintigraphy data and the correlation with the findings in the surgical intervention are reviewed.

The mean TSH at the time of repeating the MIBI was 0.12 + 0.1 mlU/L. Of the 17 patients included, the scintigraphy under thyroid suppression was positive in 13 of them (76.5%), and in the other 4 (23.5%) patients no image suggestive of adenoma was found. In the cases where the MIBI was positive after suppression, the positive predictive value (PPV) was 100%.

Suppression of thyroid function by giving thyroxine can help to improve the sensitivity of MIBI in patients with previously negative scintigraphy studies and help in the minimally invasive treatment of patients with PHPT.

Despite the different preoperative imaging modalities available for parathyroid adenoma localization, there is currently no uniform consensus on the most appropriate preoperative imaging algorithm that should be routinely followed prior to the surgical management of primary hyperparathyroidism (PHPT). We sought to determine the incremental value of adding neck ultrasonography to scintigraphy-based imaging tests.

In a single institution, surgically naive patients with PHPT underwent the following localization studies before parathyroidectomy: 1) Tc-99m sestamibi imaging with single photon emission computed tomography/computed tomography (SPECT/CT) or Tc-99m sestamibi imaging with SPECT alone, or 2) ultrasonography in addition to those tests. We retrospectively collected data and performed a multivariate analysis comparing group I (single study) to group II (addition of ultrasonography) and risk of bilateral (BNE) compared with unilateral (UNE) neck exploration.

Our study included 208 patients. Group II had 0.45 times the odds of BNE versus UNE compared with group I (unadjusted odds ratio [OR] 0.45, 95% confidence interval [CI] 0.25–0.81, p = 0.008). When adjusting for patient age, sex, preoperative calcium level, use of intraoperative PTH monitoring, preoperative PTH level, adenoma size, and number of abnormal parathyroid glands, Group II had 0.48 times the odds of BNE versus UNE compared with group I (adjusted OR 0.48, 95% CI 0.23–1.03, p = 0.06). In a subgroup analysis, only the addition of ultrasonography to SPECT decreased the risk of undergoing BNE compared with SPECT alone (unadjusted OR 0.40, 95% CI 0.19–0.84, p = 0.015; adjusted OR 0.38, 95% CI 0.15–0.96, p = 0.043).

The addition of ultrasonography to SPECT, but not to SPECT/CT, has incremental value in decreasing the extent of surgery during parathyroidectomy, even after adjusting for multiple confounding factors.

Malgré l’existence de diverses modalités d’imagerie préopératoire pour la localisation de l’adénome parathyroïdien, on déplore actuellement l’absence de consensus en ce qui concerne l’algorithme le plus approprié à suivre au chapitre de l’imagerie préalable à une prise en charge chirurgicale de l’hyperparathyroïdie primaire (HPTP). Nous avons voulu vérifier si l’ajout de l’échographie du cou aux tests d’imagerie scintigraphique offrait une valeur ajoutée.

Dans un établissement, des patients atteints d’HPTP n’ayant jamais subi d’intervention chirurgicale ont été soumis à des examens de localisation préparathyroïdectomie : 1) imagerie au moyen du sestamibi marqué au Tc-99m avec tomographie par émission monophotonique/tomodensitométrie (SPECT/CT), ou imagerie au moyen du sestamibi marqué au Tc-99m avec SPECT seule, our 2) échographie en plus de ces tests. Nous avons recueilli les données rétrospectivement et effectué une analyse multivariée pour comparer le Groupe I (examen seul) au Groupe II (ajout de l’échographie) et la probabilité qu’ils subissent une exploration cervicale bilatérale (ECB) plutôt qu’unilatérale (ECU).

Notre étude a recruté 208 patients. Le Groupe II s’est trouvé exposé à un risque 0,45 fois plus grand d’être soumis à une ECB plutôt qu’à une ECU, comparativement au Groupe I (rapport des cotes [RC] non ajusté 0,45, intervalle de confiance [IC] de 95 % 0,25–0,81, p = 0,008). Après ajustement pour tenir compte de l’âge et du sexe des patients, de leur taux préopératoire de calcium, de la surveillance peropératoire de l’HPT, du taux préopératoire de l’HPT, de la taille de l’adénome et du nombre de ganglions parathyroïdiens anormaux, le Groupe II s’est révélé exposé à un risque 0,48 fois plus grand à l’égard de l’ECB plutôt que de l’ECU comparativement au Groupe I (RC ajusté 0,48, IC de 95 % 0,23–1,03, p = 0,06). Selon une analyse de sous-groupe, seul l’ajout de l’échographie à la SPECT a réduit le risque de subir une ECB comparativement à la SPECT seule (RC non ajusté 0,40, IC de 95 % 0,19–0,84, p = 0,015; RC ajusté 0,38, IC de 95 % 0,15–0,96, p = 0,043).

L’ajout de l’échographie à la SPECT, mais non à la SPECT/CT, a offert une valeur ajoutée pour ce qui est de réduire l’étendue de l’opération durant la parathyroïdectomie, même après ajustement pour tenir compte de plusieurs facteurs de confusion.