"Primary Hyperparathyroidism (PHPT) in Children: Two Case Reports and Review of the Literature"

Primary Hyperparathyroidism in Young and Adolescents: Alike or Unlike Adult Hyperparathyroidism? - A Series from South India

Background

Primary hyperparathyroidism (PHPT) is a common endocrine condition but rare in the pediatric and adolescent populations. The presentations can be unique, accounting for significant morbidity in the case of untimely detection.

Aim

To study surgically treated pediatric PHPT retrospectively.

Methods

Surgically treated children of PHPT up to 20 years of age between 2010 to 2022 were analyzed. All of them were operated on by an endocrine surgeon and team.

Results

There was a total of 712 parathyroidectomies over 12 years, out of which there were 52 children (7.3%) had PHPT at less than 20 years of age. This group included 32 male children. The mean age was 16.1 years, including 7 cases of neonatal severe HPT. Multiple Endocrine Neoplasia type 1 was confirmed in 12 children. Presentations were more severe like bone pain (35.13%), renal stones (27.02%), incidental asymptomatic detection (18.9%), failure to thrive (10.8%), and pancreatitis (8.1%) as compared to adults. Mean serum calcium was 12.9 mg/dl (highest-14.1, N-8.8-10.8 mg/dl), mean parathormone levels were 386.91 pg/ml (N-10-65) and vitamin D levels ranged from 2.9-22.8 ng/ml. Localization was done with ultrasound and 99mTc- SESTAMIBI scans. Mean serum calcium levels in NSPHPT were 28.6 mg/dl (N-8.8-10.8 mg/dl). There were a total of 45 cases (6.32%) of PHPT less than 20 years of age, excluding the cases of NSPHPT. All children underwent parathyroidectomy, with 14 cases having an additional thymectomy, 2 cases with thyroidectomy, and a single case of hemithyroidectomy. The cure rate was 97.3%, while one baby with NSPHPT had persistent disease (postop PTH-110 pg/ml). The uniglandular disease was seen in 54.05% and the rest had a multiglandular disease. Adults accounted for 559/660 cases with 80% uniglandular disease. All cases had a postoperative histopathological confirmation with an average follow-up of 1 year.

Conclusion

Childhood PHPT has a few features same as the adult population. Symptomatic presentations like adults, though pancreatitis and fatigue were more commonly seen as compared to bone pain. Calcium, phosphorus, and parathormone levels were comparable. Uniglandular involvement was seen just like the adult population. There are a few others that make them a distinct subtype like their symptoms of bone pain and being more common among boys. One-fourth of them had MEN1. Fewer cases in this age group make them unique.

[Primary hyperparathyroidism in children]

BACKGROUND

 Primary hyperparathyroidism (PHPT) is an endocrine disorder characterized by excessive secretion of parathyroid hormone (PTH) with upper-normal or elevated blood calcium levels due to primary thyroid gland pathology. PHPT is a rare pathology in children, with a prevalence of 2-5:100,000 children according to the literature. Due to the non-specificity of clinical manifestations at onset (nausea, vomiting, abdominal pain, emotional lability), the disease may remain undiagnosed for a long time.

AIM

 To study the features of the course and molecular genetic basis of primary hyperparathyroidism in children.

MATERIALS AND METHODS

 Retrospective observational study of 49 patients diagnosed with primary hyperparathyroidism. All patients underwent a comprehensive laboratory-instrumental and molecular genetic study at the Institute of Pediatric Endocrinology, Endocrinology Research Center of Russia in the period 2014-2022.

RESULTS

 The first clinical symptoms of PHPT were noted at the age of 13.8 years [10.6; 1 5.2], among which fatigue, headaches, dyspepsia, lower limb pain, and fractures were the most common. The age of diagnosis was 15.81 years [13.1; 16.8], all children were found to have high levels of PTH, total and ionized calcium, with hypophosphatemia in 93.9% of patients (n=46) and hypercalciuria in 43% (n=21). Five out of 49 patients (10.2%) were found to have ectopy of the thyroid: 3 showed an intrathyroidal location, 2 in the mediastinal region. Molecular genetic study revealed mutations in 32.7% of patients (n=16, CI (21; 47)), mutations in MEN1 being the most frequent (n=11). Pathogenic variants in CDC73 were detected in 3 patients, RET - in 2. Among the operated 39 patients, adenoma of the thyroid was detected in 84.6% of cases (n=33), hyperplasia in 7.7% (n=3), atypical adenoma in 5.1% (n=2), carcinoma in 5.1% of cases (n=2).

CONCLUSION

 The paper presents the peculiarities of the course and the results of molecular genetic study of pediatric PHPT. This sample is the largest among those published in the Russian Federation.

[Special features of the diagnostics and treatment of hereditary primary hyperparathyroidism]

Between 2% and 10% of patients with primary hyperparathyroidism (pHPT) are diagnosed with hereditary forms of primary hyperparathyroidism (hpHPT). They are more prevalent in younger patients before the age of 40 years, in patients with persistence or recurrence of pHPT and pHPT patients with multi-glandular disease (MGD). The various forms of hpHPT diseases can be classified into four syndromes, i.e., hpHPT associated with diseases of other organ systems, and four diseases that are confined to the parathyroid glands. Approximately 40% of patients with hpHPT suffer from multiple endocrine neoplasia type 1 (MEN-1) or show germline mutations of the MEN‑1 gene. Currently, germline mutations that lead to a specific diagnosis in patients with hpHPT have currently been described in 13 different genes, which enables a clear diagnosis of the disease; however, a clear genotype-phenotype correlation does not exist, even though the complete loss of a coded protein (e.g. due to frame-shift mutations in the calcium sensing receptor, CASR) often leads to more severe clinical consequences than merely a reduced function of the protein (e.g. due to point mutation). As the various hpHPT diseases require different treatment approaches, which do not correspond to that of sporadic pHPT, a clear definition of the specific form of hpHPT must always be strived for. Therefore, before surgery of a pHPT with clinical, imaging or biochemical suspicion of hpHPT, genetic proof or exclusion of hpHPT is necessary. The differentiated treatment approach for hpHTP can only be defined by taking the clinical and diagnostic results of all the abovenamed findings into account.

Off-label use of cinacalcet in pediatric primary hyperparathyroidism: A French multicenter experience

BACKGROUND

Cinacalcet is a calcimimetic approved in adults with primary hyperparathyroidism (PHPT). Few cases reports described its use in pediatric HPT, with challenges related to the risk of hypocalcemia, increased QT interval and drug interactions. In this study, we report the French experience in this setting.

METHODS

We retrospectively analyzed data from 18 pediatric patients from 7 tertiary centers who received cinacalcet for PHPT. The results are presented as median (interquartile range).

RESULTS

At a median age of 10.8 (2.0-14.4) years, 18 patients received cinacalcet for primary HPT (N = 13 inactive CASR mutation, N = 1 CDC73 mutation, N = 1 multiple endocrine neoplasia type 1, N=3 unknown etiology). Cinacalcet was introduced at an estimated glomerular filtration rate (eGFR) of 120 (111-130) mL/min/1.73 m², plasma calcium of 3.04 (2.96-3.14) mmol/L, plasma phosphate of 1.1 (1.0-1.3) mmol/L, age-standardized (z score) phosphate of -3.0 (-3.5;-1.9), total ALP of 212 (164-245) UI/L, 25-OHD of 37 (20-46) ng/L, age-standardized (z score) ALP of -2.4 (-3.7;-1.4), PTH of 75 (59-123) ng/L corresponding to 1.2 (1.0-2.3)-time the upper limit for normal (ULN). The starting daily dose of cinacalcet was 0.7 (0.6-1.0) mg/kg, with a maximum dose of 1.0 (0.9-1.4) mg/kg per day. With a follow-up of 2.2 (1.3-4.3) years on cinacalcet therapy, PTH and calcium significantly decreased to 37 (34-54) ng/L, corresponding to 0.8 (0.5-0.8) ULN (p = 0.01), and 2.66 (2.55-2.90) mmol/L (p = 0.002), respectively. In contrast, eGFR, 25-OHD, ALP and phosphate and urinary calcium levels remained stable. Nephrocalcinosis was not reported but one patient displayed nephrolithiasis. Cinacalcet was progressively withdrawn in three patients; no side effects were reported.

CONCLUSIONS

Cinacalcet in pediatric HPT can control hypercalcemia and PTH without significant side effects.