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

2020 ◽  
Vol 2020 ◽  
Author(s):  
Jane J Tellam ◽  
Ghusoon Abdulrasool ◽  
Louise C H Ciin
Keyword(s):  
Vitamin D ◽  
Surgical Intervention ◽  
Urinary Calcium ◽  
List Type ◽  
Calcium Sensing Receptor ◽  
Clearance Ratio ◽  
Calcium Sensing ◽  
New Diagnosis ◽  
Learning Points ◽  
Parathyroid Imaging

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) <0.01 suggestive of FHH and >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.

scholarly journals Atypical Presentation of Familial Hypocalciuric Hypercalcemia: Case Report

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A182-A183
Author(s):  
Dalal S Ali ◽  
Karel Dandurand ◽  
Aliya Aziz Khan
Keyword(s):  
Vitamin D ◽  
Primary Hyperparathyroidism ◽  
Dna Analysis ◽  
Receptor Gene ◽  
Familial Hypocalciuric Hypercalcemia ◽  
Calcium Sensing Receptor ◽  
Clearance Ratio ◽  
Subtotal Parathyroidectomy ◽  
Casr Gene ◽  
Calcium Sensing

Abstract Background: Differentiation between familial hypocalciuric hypercalcemia (FHH) and primary hyperparathyroidism (PHPT) can be challenging in certain cases in the absence of DNA analysis of the calcium sensing receptor gene. The distinction between those two clinical entities with overlapping biochemical features therefore relies on the calcium to creatinine clearance ratio (CCCR), which is expected to be low in FHH (&lt;0.01 in 80% of cases and between 0.01 and 0.02 in approximately 20% of patients)1. Patients with PHPT usually have a CCCR of&gt;= 0.02. A lower CCCR between 0.01 and 0.02 can be seen in approximately 20% of patients1,2and is more commonly seen in the presence of vitamin D insufficiency, impaired renal function, low calcium intake or being of African descent. It is advised to stop drugs which can contribute to hypercalcemia and lower the CCCR such as thiazide diuretics prior to evaluating the CCCR. Clinical Case: A 56-year-old lady was referred for evaluation of persistent hypercalcemia post parathyroidectomy and fatigue. She had mildly elevated ionized serum calcium (iCa) and a mid-normal PTH with a CCCR of 0.024. She had a normal BMD with no prior fragility fractures and passed a kidney stone prior to her presentation. Physical exam was unremarkable. She had previously travelled to Tampa and had a subtotal parathyroidectomy 3 glands (RU, LU, RL) for a possible diagnosis of PHPT, tissue biopsy showed hyperplastic parathyroids. Her MEN1 gene analysis was negative for MEN1 mutation and MRI of the abdomen was unremarkable. Her mother had a diagnosis of PHPT and osteoporosis. The iCa remained mildly elevated at 1.43 mmol/L (1.15–1.3) with a 24 hr urinary CCCR at 0.024 and a mid-normal PTH of 4.4 pmol/L (1.6–6.9). Her eGFR was 104 mls/min, 25 vitamin D 82 nmol/L (75–250), 1,25 dihydroxy vitamin D 122 pmol/L (60–206), PO4 0.90 mmol/L (0.8–1.45) and alkaline phosphatase 46 U/L (35–120) were all normal. She continued to have mild symptoms of hypercalcemia and her bone scan was negative for underlying skeletal pathology. DNA studies for mutations in the CaSR gene were completed. This confirmed the presence of a heterozygous loss of function mutation in the CASR gene at c493-2A&gt;G which appears to be pathogenic. Conclusion: The CCCR is useful in differentiating PHPT from FHH however in certain cases of FHH the CCCR may be higher then expected and we have now confirmed the presence of FHH with a molecular diagnosis in a patient with a CCCR as high as 0.02. References: 1 Gunn, IR, Gaffney, D. Clinical and laboratory features of calcium-sensing receptor disorders: a systematic review. Ann Clin Biochem 2004; 41:441–58 2 Stephen J. Marx, Letter to the Editor: Distinguishing Typical Primary Hyperparathyroidism From Familial Hypocalciuric Hypercalcemia by Using an Index of Urinary Calcium, The Journal of Clinical Endocrinology & Metabolism, 2015

scholarly journals Successful use of cinacalcet to treat parathyroid-related hypercalcemia in two pediatric patients

2018 ◽  
Vol 2018 ◽  
Author(s):  
E Mogas ◽  
A Campos-Martorell ◽  
M Clemente ◽  
L Castaño ◽  
A Moreno-Galdó ◽  
...  
Keyword(s):  
Pediatric Patients ◽  
Receptor Gene ◽  
Gene Mutations ◽  
Rare Condition ◽  
List Type ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
Severe Hypercalcemia ◽  
The Right ◽  
Learning Points

Summary Two pediatric patients with different causes of hyperparathyroidism are reported. First patient is a 13-year-old male with severe hypercalcemia due to left upper parathyroid gland adenoma. After successful surgery, calcium and phosphate levels normalized, but parathormone levels remained elevated. Further studies revealed a second adenoma in the right gland. The second patient is a 13-year-old female with uncommon hypercalcemia symptoms. Presence of pathogenic calcium-sensing receptor gene (CASR) mutation was found, resulting in diagnosis of symptomatic familial hypocalciuric hypercalcemia. Cinacalcet, a calcium-sensing agent that increases the sensitivity of the CASR, was used in both patients with successful results. Learning points: Hyperparathyroidism is a rare condition in pediatric patients. If not treated, it can cause serious morbidity. Genetic tests searching for CASR or MEN1 gene mutations in pediatric patients with primary hyperparathyroidism should be performed. Cinacalcet has been effective for treating different causes of hyperparathyroidism in our two pediatric patients. Treatment has been well tolerated and no side effects have been detected.

scholarly journals A novel CASR variant in a family with familial hypocalciuric hypercalcaemia and primary hyperparathyroidism

2020 ◽  
Vol 2020 ◽  
Author(s):  
Satyanarayana V Sagi ◽  
Hareesh Joshi ◽  
Jamie Trotman ◽  
Terence Elsey ◽  
Ashwini Swamy ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Primary Hyperparathyroidism ◽  
Organ Damage ◽  
Urinary Calcium ◽  
Interesting Case ◽  
List Type ◽  
Loss Of Function ◽  
Clearance Ratio ◽  
Hormone Levels ◽  
Severe Hypercalcaemia

Summary Familial hypocalciuric hypercalcaemia (FHH) is a dominantly inherited, lifelong benign disorder characterised by asymptomatic hypercalcaemia, relative hypocalciuria and variable parathyroid hormone levels. It is caused by loss-of-function pathogenic variants in the calcium-sensing receptor (CASR) gene. Primary hyperparathyroidism (PHPT) is characterised by variable hypercalcaemia in the context of non-suppressed parathyroid hormone levels. Unlike patients with FHH, patients with severe hypercalcaemia due to PHPT are usually symptomatic and are at risk of end-organ damage affecting the kidneys, bone, heart, gastrointestinal system and CNS. Surgical resection of the offending parathyroid gland(s) is the treatment of choice for PHPT, while dietary adjustment and reassurance is the mainstay of management for patients with FHH. The occurrence of both FHH and primary hyperparathyroidism (PHPT) in the same patient has been described. We report an interesting case of FHH due to a novel CASR variant confirmed in a mother and her two daughters and the possible coexistence of FHH and PHPT in the mother, highlighting the challenges involved in diagnosis and management. Learning points: Familial hypocalciuric hypercalcaemia (FHH) and primary hyperparathyroidism (PHPT) can coexist in the same patient. Urinary calcium creatinine clearance ratio can play a role in distinguishing between PHPT and FHH. Genetic testing should be considered in managing patients with PHPT and FHH where the benefit may extend to the wider family. Family segregation studies can play an important role in the reclassification of variants of uncertain significance. Parathyroidectomy has no benefit in patients with FHH and therefore, it is important to exclude FHH prior to considering surgery. For patients with coexisting FHH and PHPT, parathyroidectomy will reduce the risk of complications from the severe hypercalcaemia associated with PHPT.

Thick ascending limb claudins are altered to increase calciuria and magnesiuria in metabolic acidosis

2021 ◽  
Author(s):  
Il Hwan Oh ◽  
Chor Ho Jo ◽  
Sua Kim ◽  
Sungsin Jo ◽  
Sungjin Chung ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Immunofluorescence Microscopy ◽  
Urinary Calcium ◽  
Receptor Protein ◽  
Thick Ascending Limb ◽  
Sprague Dawley ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
Sprague Dawley Rats ◽  
Calcium And Magnesium

Urinary calcium and magnesium wasting is a characteristic feature of metabolic acidosis, and this study focused on the role of the thick ascending limb of Henle's loop in metabolic acidosis-induced hypercalciuria and hypermagnesiuria because thick ascending limb is an important site of paracellular calcium and magnesium reabsorption. Male Sprague-Dawley rats were used to determine the effects of acid loading (by adding NH4Cl 7.2 mmol/220 g BW/d to food slurry for 7 days) on renal expression of claudins and then to evaluate whether the results were reversed by antagonizing calcium-sensing receptor (using NPS-2143). At the end of each animal experiment, the kidneys were harvested for immunoblotting, immunofluorescence microscopy and qPCR analysis of claudins and the calcium-sensing receptor. As expected, NH4Cl loading lowered urinary pH and increased excretion of urinary calcium and magnesium. In NH4Cl-loaded rats, renal protein and mRNA expression of claudin-16, and claudin-19 decreased compared with controls. However, claudin-14 protein and mRNA increased in NH4Cl-loaded rats. Consistently, the calcium-sensing receptor protein and mRNA were upregulated in NH4Cl-loaded rats. All these changes were reversed by NPS-2143 coadministration and were confirmed using immunofluorescence microscopy. Hypercalciuria and hypermagnesiuria in NH4Cl-loaded rats were significantly ameliorated by NPS-2143 coadministration as well. We conclude that in metabolic acidosis, claudin-16 and claudin-19 in the thick ascending limb are downregulated to produce hypercalciuria and hypermagnesiuria via the calcium-sensing receptor.

scholarly journals Simultaneous expression analysis of vitamin D receptor, calcium-sensing receptor, cyclin D1, and PTH in symptomatic primary hyperparathyroidism in Asian Indians

2013 ◽  
Vol 169 (1) ◽  
pp. 109-116 ◽  
Author(s):  
Shweta Varshney ◽  
Sanjay Kumar Bhadada ◽  
Uma Nahar Saikia ◽  
Naresh Sachdeva ◽  
Arunanshu Behera ◽  
...  
Keyword(s):  
Vitamin D ◽  
Primary Hyperparathyroidism ◽  
Cyclin D1 ◽  
Vitamin D Receptor ◽  
Asian Indians ◽  
Parathyroid Tissue ◽  
Fold Change ◽  
Mrna Levels ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing

BackgroundTo explore underlying molecular mechanisms in the pathogenesis of symptomatic sporadic primary hyperparathyroidism (PHPT).Materials and methodsForty-one parathyroid adenomas from patients with symptomatic PHPT and ten normal parathyroid glands either from patients with PHPT (n=3) or from euthyroid patients without PHPT during thyroid surgery (n=7) were analyzed for vitamin D receptor (VDR), calcium-sensing receptor (CASR), cyclin D1 (CD1), and parathyroid hormone (PTH) expressions. The protein expressions were assessed semiquantitatively by immunohistochemistry, based on percentage of positive cells and staining intensity, and confirmed by quantitative real-time PCR.ResultsImmunohistochemistry revealed significant reductions in VDR (both nuclear and cytoplasmic) and CASR expressions and significant increases in CD1 and PTH expressions in adenomatous compared with normal parathyroid tissue. Consistent with immunohistochemistry findings, bothVDRandCASRmRNAs were reduced by 0.36- and 0.45-fold change (P<0.001) andCD1andPTHmRNAs were increased by 9.4- and 17.4-fold change respectively (P<0.001) in adenomatous parathyroid tissue.PTHmRNA correlated with plasma PTH (r=0.864;P<0.001), but not with adenoma weight, whileCD1mRNA correlated with adenoma weight (r=0.715;P<0.001). There were no correlations betweenVDRandCASRmRNA levels and serum Ca, plasma intact PTH, or 25-hydroxyvitamin D levels. In addition, there was no relationship between the decreases inVDRandCASRmRNA expressions and the increases inPTHandCD1mRNA expressions.ConclusionsThe expression of both VDR and CASR are reduced in symptomatic PHPT in Asian Indians. In addition,CD1expression was greatly increased and correlated with adenoma weight, implying a potential role for CD1 in adenoma growth and differential clinical expression of PHPT.

Vitamin D receptor, a tumor suppressor in skin

2015 ◽  
Vol 93 (5) ◽  
pp. 349-354 ◽  
Author(s):  
Daniel D. Bikle
Keyword(s):  
Vitamin D ◽  
Tumor Suppressor ◽  
Vitamin D Receptor ◽  
Tumor Formation ◽  
Calcium Sensing Receptor ◽  
Keratinocyte Proliferation ◽  
Calcium Sensing ◽  
Damage Repair ◽  
Proliferation And Differentiation ◽  
Active Investigation

Vitamin D and calcium are well-established regulators of keratinocyte proliferation and differentiation. Therefore, it was not a great surprise that deletion of the vitamin D receptor (VDR) should predispose the skin to tumor formation, and that the combination of deleting both the VDR and calcium sensing receptor (CaSR) should be especially pro-oncogenic. In this review I have examined 4 mechanisms that appear to underlie the means by which VDR acts as a tumor suppressor in skin. First, DNA damage repair is curtailed in the absence of the VDR, allowing mutations in DNA to accumulate. Second and third involve the increased activation of the hedgehog and β-catenin pathways in the epidermis in the absence of the VDR, leading to poorly regulated proliferation with reduced differentiation. Finally, VDR deletion leads to a shift in the expression of long noncoding RNAs toward a more oncogenic profile. How these different mechanisms interact and their relative importance in the predisposition of the VDR null epidermis to tumor formation remain under active investigation.

scholarly journals Vitamin D Receptor and Calcium Sensing Receptor Polymorphisms and the Risk of Colorectal Cancer in European Populations

2009 ◽  
Vol 18 (9) ◽  
pp. 2485-2491 ◽  
Author(s):  
M. Jenab ◽  
J. McKay ◽  
H. B. Bueno-de-Mesquita ◽  
F. J.B. van Duijnhoven ◽  
P. Ferrari ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Vitamin D ◽  
Vitamin D Receptor ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
European Populations
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