Think twice: a rare calcium sensing receptor mutation and a new diagnosis of familial hypocalciuric hypercalcaemia

Autor: Ghusoon Abdulrasool, Louise C H Ciin, Jane J Tellam
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Male
Sestamibi scan
Hypercalcaemia
Parathyroid
endocrine system diseases
Endocrinology
Diabetes and Metabolism

medicine.medical_treatment
White
Gastroenterology
lcsh:Diseases of the endocrine glands. Clinical endocrinology
Error in Diagnosis/Pitfalls and Caveats
0302 clinical medicine
Palpitations
DNA sequencing
Vitamin D
Hypocalciuria
Fatigue
Parathyroid adenoma
education.field_of_study
Parathyroid hyperplasia
Calcium to creatinine clearance ratio
Urinary calcium
030220 oncology & carcinogenesis
Calcium-sensing receptor
medicine.symptom
PTH
Parathyroidectomy
Adult
medicine.medical_specialty
Population
030209 endocrinology & metabolism
03 medical and health sciences
Internal medicine
Internal Medicine
medicine
Genetics
education
June
lcsh:RC648-665
business.industry
Familial hypocalciuric hypercalcaemia
Australia
Neuroendocrinology
medicine.disease
Calcium (urine)
Diet
business
Primary hyperparathyroidism
Hypervitaminosis D
Molecular genetic analysis
Zdroj: Endocrinology, Diabetes & Metabolism Case Reports
Endocrinology, Diabetes & Metabolism Case Reports, Vol 1, Iss 1, Pp 1-5 (2020)
ISSN: 2052-0573
Popis: Summary Distinguishing primary hyperparathyroidism (PHPT) from familial hypocalciuric hypercalcaemia (FHH) can be challenging. Currently, 24-h urinary calcium is used to differentiate between the two conditions in vitamin D replete patients, with urinary calcium creatinine clearance ratio (UCCR) 0.02 supportive of PHPT. A 26-year-old Caucasian gentleman presented with recurrent mild hypercalcaemia and inappropriately normal parathyroid hormone (PTH) following previous parathyroidectomy 3 years prior. He had symptoms of fatigue and light-headedness. He did not have any other symptoms of hypercalcaemia. His previous evaluation appeared to be consistent with PHPT as evidenced by hypercalcaemia with inappropriately normal PTH and UCCR of 0.0118 (borderline low using guidelines of >0.01 consistent with PHPT). He underwent parathyroidectomy and three parathyroid glands were removed. His calcium briefly normalised after surgery, but rose again to pre-surgery levels within 3 months. Subsequently, he presented to our centre and repeated investigations showed 24-h urinary calcium of 4.6 mmol/day and UCCR of 0.0081 which prompted assessment for FHH. His calcium-sensing receptor (CASR) gene was sequenced and a rare inactivating variant was detected. This variant was described once previously in the literature. His mother was also confirmed to have mild hypercalcaemia with hypocalciuria and, on further enquiry, had the same CASR variant. The CASR variant was classified as likely pathogenic and is consistent with the diagnosis of FHH. This case highlights the challenges in differentiating FHH from PHPT. Accurate diagnosis is vital to prevent unnecessary surgical intervention in the FHH population and is not always straightforward. Learning points: Distinguishing FHH from PHPT with co-existing vitamin D deficiency is difficult as this can mimic FHH. Therefore, ensure patients are vitamin D replete prior to performing 24-h urinary calcium collection. Individuals with borderline UCCR could have either FHH or PHPT. Consider performing CASR gene sequencing for UCCR between 0.01 and 0.02. Parathyroid imaging is not required for making the diagnosis of PHPT. It is performed when surgery is considered after confirming the diagnosis of PHPT.
Databáze: OpenAIRE