Imaging features of hypercalcemia: A primer for emergency radiologists.

Hypercalcemia is a marker for a wide variety of underlying etiologies, and its presentation in the emergency setting may be asymptomatic, incidental, or a primary complaint with associated symptoms and physical exam findings. While the workup is initially driven through serum laboratory testing, imaging plays an important role in diagnosis and post-treatment follow up. This review covers multiple common and uncommon etiologies of hypercalcemia, details their underlying mechanisms, and identifies the most important associated imaging findings. It is important for radiologists to be familiar with these etiologies and imaging findings, particularly in the emergency setting since hypercalcemia may represent the only significant laboratory abnormality associated with the presenting condition. Furthermore, the radiologist's interpretation of a study may be directly influenced by knowing about a patient's hypercalcemia.

Multiple endocrinopathies, hypercalcaemia and pancreatitis following combined immune checkpoint inhibitor use- case report and review of literature.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are a novel class of oncological agents which are used to treat a number of malignancies. To date seven agents have been approved by the Food and Drug Administration (FDA) to treat both solid and haematological malignancies. Despite their efficacy they have been associated with a number of endocrinopathies. We report a unique case of hypophysitis, thyroiditis, severe hypercalcaemia and pancreatitis following combined ICI therapy. CASE PRESENTATION: A 46-year old Caucasian female with a background history of malignant melanoma and lung metastases presented to the emergency department with lethargy, nausea, palpitations and tremors. She had been started on a combination of nivolumab and ipilimumab 24 weeks earlier. Initial investigations revealed thyrotoxicosis with a thyroid stimulating hormone (TSH) of < 0.01 (0.38-5.33) mIU/L, free T4 of 66.9 (7-16) pmol/.L. TSH receptor and thyroperoxidase antibodies were negative. She was diagnosed with thyroiditis and treated with a beta blocker. Six weeks later she represented with polyuria and polydipsia. A corrected calcium of 3.54 (2.2-2.5) mmol/l and parathyroid hormone (PTH) of 9 (10-65) pg/ml confirmed a diagnosis of non-PTH mediated hypercalcaemia. PTH-related peptide and 1, 25-dihydroxycholecalciferol levels were within the normal range. Cross-sectional imaging and a bone scan out ruled bone metastases but did reveal an incidental finding of acute pancreatitis - both glucose and amylase levels were normal. The patient was treated with intravenous hydration and zoledronic acid. Assessment of the hypothalamic-pituitary-adrenal (HPA) axis uncovered adrenocorticotrophic hormone (ACTH) deficiency with a morning cortisol of 17 nmol/L. A pituitary Magnetic Resonance Image (MRI) was unremarkable. Given her excellent response to ICI therapy she remained on ipilimumab and nivolumab. On follow-up this patient's thyrotoxicosis had resolved without anti-thyroid mediations - consistent with a diagnosis of thyroiditis secondary to nivolumab use. Calcium levels normalised rapidly and remained normal. ACTH deficiency persisted, and she is maintained on oral prednisolone. CONCLUSION: This is a remarkable case in which ACTH deficiency due to hypophysitis; thyroiditis; hypercalcaemia and pancreatitis developed in the same patient on ipilimumab and nivolumab combination therapy. We postulate that hypercalcaemia in this case was secondary to a combination of hyperthyroidism and secondary adrenal insufficiency.

Misleading localization by 18F-fluorocholine PET/CT in familial hypocalciuric hypercalcemia type-3: a case report.

BACKGROUND: Familial hypocalciuric hypercalcemia (FHH) is a heterogeneous autosomal-dominant disorder of calcium hemostasis that may be difficult to distinguish clinically from mild primary hyperparathyroidism. Loss-of-function mutations mainly involving Arg15 residue of the adaptor-related protein complex 2, sigma subunit 1 (AP2S1) cause a rarer, more recently recognized form of FHH, FFH type-3. Recently, 18F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) showed superior sensitivity to conventional imaging in localizing parathyroid adenomas. We report a new FFH type-3 patient who underwent unnecessary parathyroidectomy in association with misleading FCH-PET/CT imaging. CASE PRESENTATION: A 29-year old woman was initially evaluated for parathyroid hormone (PTH)-dependent hypercalcemia in 2013. Medical history was positive only for chronic constipation and malaise with no personal or family history of hypercalcemia, kidney stones, or neck surgery. Over seven years, serum calcium level was 2.51-2.89 mmol/L with concomitant PTH level of 58.7-94.8 mmol/L. Serum phosphate levels were in the low/low normal range. Serum creatinine and magnesium levels were normal. 25-hydroxy vitamin D level was 13 nmol/L. 24-hour urine calcium level was 1.92 mmol/day but increased to 6.99 mmol/day after treatment with cholecalciferol 1000 IU daily. Bone mineral density and renal ultrasound were normal. Parathyroid ultrasound showed two hypoechoic nodules inferior to the left and right thyroid lobes; however, 99mtechnitium-sestamibi scans (2013, 2016, 2018) were negative. FCH-PET/CT (2019) showed focal uptake co-localizing with the nodule inferior to the left thyroid lobe. The patient underwent left inferior parathyroidectomy and pathology was consistent with parathyroid hyperplasia. However, postoperatively, serum calcium and PTH levels remained elevated and FCH-PET/CT and ultrasound showed persistence of the uptake/nodule. Whole exome sequencing showed Arg15Cys mutation in the AP2S1 gene characteristic of FHH type-3. CONCLUSIONS: In this new case of FHH type-3, FCH-PET/CT failed to localize to the hyperplastic parathyroid glands and localized instead to apparently a lymph node. This, together with increased urinary calcium after vitamin D supplementation, led to unnecessary parathyroidectomy. Given the increasingly lower cost of genetic testing and the cost of follow up and unnecessary surgery, it may prudent to include genetic testing for FHH early on in patients with mild PTH-dependent hypercalcemia.

Co-Existence of Sarcoidosis and Sjögren's Syndrome with Hypercalcemia and Renal Involvement: A Case Report and Literature Review.

BACKGROUND: Sarcoidosis and Sjögren's syndrome (SS) are chronic multi-system inflammatory diseases of unknown origin that most commonly attack the salivary glands. Both of the diseases have vague and non-specific symptoms, causing difficulties for the clinicians to distinguish between the two diseases. Main diagnostic criteria of SS exclude sarcoidosis. However, a co-existence of both diseases should be noted. Here, a case of co-existing sarcoidosis and Sjögren's syndrome is reported, complicated with severe hypercalcemia and renal failure, in addition to a literature review. CASE PRESENTATION: A 71-year-old man visited our hospital complaining of daily progressive oral dryness, thirst, and blurred vision with a feeling of dry eyes for a one-year duration. His physical examination showed enlargement of both sides of cervical and supraclavicular lymph nodes. Lung auscultation showed decreased breath sounds with bibasilar inspiratory crackles. However, initial laboratory results revealed severe hypercalcemia with moderate hypercalciuria and renal failure. The final diagnosis was co-existing SS and sarcoidosis according to clinical, radiological, and laboratory data. The patient received oral prednisone therapy for 18 months. After a follow-up of years, the serum calcium concentration, renal function, and chest CT scan remained normal after prednisone treatment stopped for more than 18 months. CONCLUSION: In the literature, calcium metabolic disorder and renal involvement have not been reported among patients with Sarcoidosis and Sjögren's syndrome, suggesting that calcium metabolic disorder may be underestimated. Serum and urine calcium concentration should be measured in addition to routine laboratory tests.

Familial hypocalciuric hypercalcemia in an index male: grey zones of the differential diagnosis from primary hyperparathyroidism in a 13-year clinical follow up.

Familial hypocalciuric hypercalcemia (FHH) type 1, caused by a heterozygous inactivating mutation of the gene encoding the calcium-sensing receptor (CaSR), is characterized by mild to moderate hypercalcemia, hypocalciuria and inappropriately normal or elevated parathyroid hormone (PTH). FHH must be differentiated from primary hyperparathyroidism (PHPT) because parathyroidectomy is ineffective in the former. Herein, we report a 39-year-old male patient with a 13-year history of asymptomatic PTH-dependent hypercalcemia (mean calcium of 2.88 mmol/l; reference range 2.15-2.55 mmol/l) and calcium-to-creatinine clearance ratio (Ca/Cr) ranging from 0.007 to 0.0198, which is consistent with either FHH or PHPT. Although a family history of hypercalcemia was negative, and PET-CT with fluorocholine was suggestive of a parathyroid adenoma, genetic analysis of the CaSR gene identified a heterozygous inactivating mutation NM_000388.4:c.1670G>A p. (Gly557Glu) in exon 6 and a polymorphism NM_000388.4:c.1192G>A p. (Asp398Asn) in exon 4. The G557E mutation has been previously reported in a Japanese family in which all family members with the mutation had Ca/Cr below 0.01 consistent with FHH. The biochemical profile of FHH and PHPT may overlap. Our FHH patient with a G557E CaSR mutation illustrates that the differential diagnosis can be difficult in an index case with no family history, (false) positive parathyroid imaging and higher calciuria than expected for FHH. Calcium intake, vitamin D status and bone resorption might have contributed to the Ca/Cr variations over a 13-year clinical follow up. This case thus emphasizes the irreplaceable role of genetic testing of the CaSR gene when clinical evaluation is inconclusive.

Paradoxical scintigraphy bone scan findings with malignancy-associated extreme hypercalcemia.

We report the first case of extreme hypercalcemia (Ca 2+ >6.0 mmol/L) as the initial presentation of de novo metastatic breast cancer. Following treatment and stabilization of the patient, imaging revealed a large breast mass and widespread osseous metastases. Whole body bone scintigraphy demonstrated significant extra osseous uptake of radiotracer in the lungs, liver, and kidneys-a rare phenomenon secondary to profound hypercalcemia. Biopsy revealed estrogen receptor (ER) positive breast carcinoma, for which the patient was treated.

Löfgren Syndrome with Hypercalcemia and Neuroendocrinological Involvement: A Case Report.

BACKGROUND: Sarcoidosis is a systemic inflammatory disease of unknown etiology that can affect virtually any organ. Löfgren syndrome, characterized by erythema nodosum, hilar lymphadenopathy, fever and polyarthritis, represents only 20-30% of the cases of sarcoidosis. Only 2- 10% of the cases feature hypercalcemia. CASE: The case of a 42-year-old Hispanic woman with a history of erythema nodosum and three weeks of nausea, emesis, constipation, asthenia, adynamia, polydipsia, and somnolence, concomitant with hypercalcemia, but normal parathyroid hormone (PTH) and 25-hydroxyvitamin D has been presented. The initial diagnostic approach was based upon the suspicion of multiple myeloma or bone metastases; however, further findings of bilateral hilar lymphadenopathy, elevated serum angiotensin-converting enzyme (ACE) and a right inguinal lymphadenomegaly suggested an alternate diagnosis. Biopsy of the latter supported sarcoidosis as the diagnosis. She was successfully treated in the hospital with zoledronic acid and as an outpatient with immunosuppressive therapy. Persistence of a previously undisclosed symptom of oligomenorrhea led to the detection of hyperprolactinemia secondary to hypophyseal infiltration, refractory to immunosuppressive therapy but with an adequate response to cabergoline. CONCLUSION: This case strays from Löfgren Syndrome's expected behavior, presenting a more progressive, multisystemic disease. This case report was written in adherence to the CARE guidelines of 2013 to include information in it.

Rare Hereditary Burden associated with a Hypercalcemic Small-Cell Carcinoma of Cervix in a Young Female Patient.

BACKGROUND: Oncological diseases have, in most cases, a multifactorial etiology, composed of a combination of external and internal environmental factors. Hereditary tumorous syndromes are mostly autosomal dominant diseases with incomplete but very high penetrance. OBSERVATION: The patient, an 18-year-old virgin female, consulted a gynecologist in June 2018 because of metrorrhagia. Magnetic resonance imaging revealed a cervical tumor with the dimensions 80 × 90 × 80 mm. Histological analysis confirmed the presence of a very rare hypercalcemic type of small-cell carcinoma of the cervix. Further investigation of the germinal exom of the patient showed pathological variations in genes PALB2 and BRCA2, presented with recommendation of detailed examination by medical genetics. CONCLUSION: Clinical experience with this type of tumor is very limited, but it still comes with some useful outcome. Small cell carcinomas of the gynecologic tract are very rare, aggressive diseases, with very poor prognosis, affecting mainly young women. Their origin is most often the ovaries, based on most clinical data, but these tumor also localize to the endometrium, cervix, vagina and vulva. It is an extremely rare type of cancer, for which clinical data is scant due to the extremely low number of reported cases. In this patient, the carcinoma had an unusual genetical mutation burden, which she inherited from her parents. In the light of these findings, we recommend that patients suspected of having a small-cell of the gynecologic tract provide a detailed family history, and that genetic testing be considered in similar cases. This work was supported by MH CR grant 16-33209A and research program of Charles University Progress Q40/06. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 10. 6. 2019 Accepted: 9. 9. 2019.

Ultrasonographic size of the canine parathyroid gland may not correlate with histopathology.

Accurate ultrasonographic differentiation of normal versus abnormal parathyroid glands is important for clinical workup and presurgical screening in dogs with hypercalcemia. In previous published studies, size has been the only ultrasonographic criterion correlated with histologic diagnoses of abnormal parathyroid glands. In this retrospective, cross-sectional study, the medical records of dogs with ultrasonographic examinations of the parathyroid glands and histologic diagnoses of parathyroid gland hyperplasia, adenoma, and adenocarcinoma were evaluated. Ultrasonographic characteristics were recorded for each gland and compared among histologic diagnosis groups. A total of 49 dogs and 59 parathyroid glands were sampled and assigned to the following groups for analyses: adenoma (n = 24), hyperplastic (n = 20), and adenocarcinoma (n = 15). There were no associations with dog age, sex, weight, breed; or gland laterality, location, ultrasonographic shape, or echogenicity among histologic diagnosis groups (P > .05). Parathyroid gland adenocarcinomas were found to be less likely to have a homogeneous echotexture on ultrasonographic evaluation, with hyperplastic glands being smaller (P = .022) and adenocarcinomas being larger (P = .042). While 3 mm was the optimum cutoff for differentiating hyperplastic and neoplastic parathyroid glands in this sample of dogs, values varied widely within groups and there were overlapping values between groups. Therefore, authors caution against using ultrasonographic size as a sole criterion for differentiating hyperplasia from neoplasia and normal versus abnormal parathyroid glands.

Refractory hypercalcemia due to an ectopic mediastinal parathyroid gland in a hemodialysis patient: a case report.

BACKGROUND: Hypercalcemia crisis is a complex disorder rarely induced by tertiary hyperparathyroidism, which clinically presents as nonsuppressible parathyroid hyperplasia with persistent increased PTH levels and hypercalcemia. It is one of the major risk factors of morbidity and mortality in end-stage renal disease. Parathyroidectomy should be in consideration in dialysis patients with severe hyperparathyroidism who are refractory to medical therapy. The implications and consequences of it, however, are not fully understood. CASE PRESENTATION: We present a case of a 70 year-old man disturbed by gastrointestinal manifestations due to hypercalcaemic crisis. The patient had longstanding hypercalcaemia and hyperparathyrodism refractory to calcimimetics, calcitonin, hormone and haemodialysis. A ectopic parathyroid gland in anterior mediastinum was found and elucidated by Tc-99 m scan. Futhermore, a video-assisted thoracoscopic parathyroidectomy was performed. Histologically, the tumour consisted of densely arranged chief cells immunohistochemically positive for PTH antigens. Consequently, calcium and parathormone were declining stably without any complications. CONCLUSIONS: On account of refractory hypercalcemia and hyperparathyroidism, radionuclide scanning is useful in the diagnosis of ectopic parathyroid gland. it is of great significance for multidisciplinary therapy combing anesthesia, surgical, endocrinology and nephrology staff.

PETC/CT with 18F-Choline localizes hyperfunctioning parathyroid adenomas equally well in normocalcemic hyperparathyroidism as in overt hyperparathyroidism.

PURPOSE: Identification of pathologic parathyroid glands in primary hyperparathyroidism, traditionally based on neck ultrasound (US) and/or 99mTc-Sestamibi scintigraphy, can be challenging. PET/CT with 18F-Fluorocholine (18F-FCH) might improve the detection of pathologic parathyroid glands. We aimed at comparing the diagnostic performance of 18F-FCH-PET/CT with that of dual-phase dual-isotope parathyroid scintigraphy and neck US. METHODS: Thirty-four consecutive patients with primary hyperparathyroidism were prospectively enrolled, 7 had normocalcemic hyperparathyroidism, and 27 had classic hypercalcemic hyperparathyroidism. All patients underwent high-resolution neck US, dual-phase dual-isotope 99mTc-Pertechnetate/99mTc-Sestamibi scintigraphy, and 18F-FCH-PET/CT. RESULTS: In the whole patients' group, the detection rates of the abnormal parathyroid gland were 68% for neck US, 71% for 18F-FCH-PET/CT, and only 15% for 99mTc-Sestamibi scintigraphy. The corresponding figures in normocalcemic and hypercalcemic hyperparathyroidism were 57 and 70% for neck US, 70 and 71% for 18F-FCH-PET/CT, and 0 and 18% for 99mTc-Sestamibi scintigraphy, respectively. In the 17 patients in whom the abnormal parathyroid gland was identified, either at surgery or at fine needle aspiration cytology/biochemistry, the correct detection rate was 82% for neck US, 89% for 18F-FCH-PET/CT, and only 17% for 99mTc-Sestamibi scintigraphy. CONCLUSIONS: 18F-FCH-PET/CT can be considered a first-line imaging technique for the identification of pathologic parathyroid glands in patients with normocalcemic and hypercalcemic hyperparathyroidism, even when the parathyroid volume is small.

Rare Cause of Infantile Hypercalcemia: A Novel Mutation in the SLC34A1 Gene.

BACKGROUND: Under physiological conditions, proximal tubular phosphate reabsorption via NaPi-IIa (and NaPi-IIc) ensures the maintenance of phosphate homeostasis. Impairment of NaPi-IIa, encoded by SLC34A1, is associated with various overlapping clinical syndromes, including hypophosphatemic nephrolithiasis with osteoporosis, renal Fanconi's syndrome with chronic kidney disease, and idiopathic infantile hypercalcemia and nephrocalcinosis. METHODS: A patient was referred to our hospital due to hyponatremia, hyperkalemia, and hypophosphatemia, as well as persistent hypercalcemia after fluid therapy and sodium replacement. At admission to our hospital, potassium and sodium values were normal. After initiation of phosphorus therapy, hypokalemia and metabolic alkalosis were observed. Renal sonography showed bilateral medullary nephrocalcinosis. Analyses of the SLC34A1 gene were performed due to hypercalcemia and hypophosphatemia. RESULTS: Gene analyses identified a novel homozygous c.682T>C (p.W228R) (p.Trp228Arg) mutation. There are no previous reports of patients with SLC34A1 gene mutations presenting with hypokalemia and metabolic alkalosis. CONCLUSION: Herein, we present a case of infantile hypercalcemia 2 with a very different phenotype from that of previously described patients. Our findings provide further evidence for the wide range of phenotypic heterogeneity associated with NaPi-IIa impairment.

Acute hypercalcemia and excessive bone resorption following anti-RANKL withdrawal: Case report and brief literature review.

Denosumab is an anti-RANKL antibody that is commonly used for the treatment of osteoporosis; in oncology, bisphosphonates and denosumab have become the standard therapies for the treatment and prevention of skeletal complications in patients with myeloma and solid tumors. In recent years, excessive bone remodeling following the discontinuation of denosumab has raised concerns. Several cases of hypercalcemia have been reported after the discontinuation of high-dose denosumab (120 mg every 4 weeks), mainly in children. In this study, we report a new case of severe refractory hypercalcemia in a 54-year-old woman who received high-dose denosumab for 5 years as an adjuvant therapy for breast cancer. She is currently in remission and undergoing treatment with anastrazole, an aromatase inhibitor. The peculiarities of this case are the presence of associated bone pain with subperiosteal bone resorption on hand X-rays, and diffuse, long bone diaphyseal uptake on a bone scan. Hyperparathyroidism has been ruled out, and existing evidence suggests that this high-level of bone remodeling could be due to a rebound hyperactivation of the RANKL pathway. In addition to rehydration, repeated use of i.v. bisphosphonates was required to control recurrent hypercalcemia. As hypercalcemia is a serious metabolic complication, a gradual dose reduction should be considered when interruption of high dose denosumab therapy is planned.

Hipercalcemia severa en el curso de rabdomiolisis: caso clínico / Rhabdomyolysis and severe hypercalcemia: report of one case

Rhabdomyolysis (RD) is the process that leads to cell destruction of striated muscle. Causes include inherited metabolic defects or acquired disorders. RD is frequently associated with acute kidney injury (AKI) and disorders of calcium metabolism. We report a 33 year old man that after amphetamine consumption and an uninterrupted 3,000 km driving presented vomiting, muscle pain and dark urine. He had elevated creatinkinase levels, severe hypocalcemia and an acute renal failure. He was treated with hemodialysis and calcitriol. He was transferred to our hospital and on admission a serum calcium of 18 mg/dl was detected. He continued on hemodialysis, recovering renal function and with normalization of creatinkinase levels and serum calcium level.

Hypercalcemia and osteolytic bone lesions as the major symptoms in a chronic lymphocytic leukemia/small lymphocytic lymphoma patient: a rare case.

We report a 40-year-old woman who presented with multiple osteolytic bone lesions and hypercalcemia, which are rarely caused by chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Although receiving intensive chemotherapy and allogeneic transplantation, the patient had a poor outcome with an overall survival of 2 years. To our knowledge, this presentation is extremely rare for B-chronic lymphocytic leukemia, and new treatment strategies may be needed for long-term control of the disease.

Unique Variant of NOD2 Pediatric Granulomatous Arthritis With Severe 1,25-Dihydroxyvitamin D-Mediated Hypercalcemia and Generalized Osteosclerosis.

Pediatric granulomatous arthritis (PGA) refers to two formerly separate entities: autosomal dominant Blau syndrome (BS) and its sporadic phenocopy early-onset sarcoidosis (EOS). In 2001 BS and in 2005 EOS became explained by heterozygous mutations within the gene that encodes nucleotide-binding oligomerization domain-containing protein 2 (NOD2), also called caspase recruitment domain-containing protein 15 (CARD15). NOD2 is a microbe sensor in leukocyte cytosol that activates and regulates inflammation. PGA is characterized by a triad of autoinflammatory problems (dermatitis, uveitis, and arthritis) in early childhood, which suggests the causal NOD2/CARD15 mutations are activating defects. Additional complications of PGA were recognized especially when NOD2 mutation analysis became generally available. However, in PGA, hypercalcemia is only briefly mentioned, and generalized osteosclerosis is not reported, although NOD2 regulates NF-κB signaling essential for osteoclastogenesis and osteoclast function. Herein, we report a 4-year-old girl with PGA uniquely complicated by severe 1,25(OH)2 D-mediated hypercalcemia, nephrocalcinosis, and compromised renal function together with radiological and histopathological features of osteopetrosis (OPT). The classic triad of PGA complications was absent, although joint pain and an antalgic gait accompanied wrist, knee, and ankle swelling and soft non-tender masses over her hands, knees, and feet. MRI revealed tenosynovitis in her hands and suprapatellar effusions. Synovial biopsy demonstrated reactive synovitis without granulomas. Spontaneous resolution of metaphyseal osteosclerosis occurred while biochemical markers indicated active bone turnover. Anti-inflammatory medications suppressed circulating 1,25(OH)2 D, corrected the hypercalcemia, and improved her renal function, joint pain and swelling, and gait. Mutation analysis excluded idiopathic infantile hypercalcemia, type 1, and known forms of OPT, and identified a heterozygous germline missense mutation in NOD2 common in PGA (c.1001G>A, p.Arg334Gln). Thus, radiological and histological findings of OPT and severe hypercalcemia from apparent extrarenal production of 1,25(OH)2 D can complicate NOD2-associated PGA. Although the skeletal findings seem inconsequential, treatment of the hypercalcemia is crucial to protect the kidneys. © 2018 American Society for Bone and Mineral Research.

Hypercalcemic crisis in third trimenon: evaluating the optimal treatment strategy.

Hypercalcemia due to primary hyperparathyroidism during pregnancy is a rare condition and associated with increased morbidity and mortality for the mother and the unborn child. Whereas parathyroidectomy is favored during the second trimester, no clear recommendations exist for its management during the third trimenon. We here report the case of a 26-year-old woman in the 29th week of her first pregnancy, who was admitted to our clinic with hypertension, intra-uterine growth retardation and polyhydramnios. Severe hypercalcemia due to primary hyperparathyroidism was diagnosed (total calcium 3.34 mmol/l; PTH 216 pg/ml), but no enlarged parathyroid gland could be localized by ultrasound. Treatment with calcitonin and cinacalcet could not control hypercalcemia. Therefore explorative surgery was performed and a single parathyroid adenoma was resected, resulting in normalization of serum calcium levels. The surgical procedure was tolerated well by the mother and fetus. Hypercalcemia-induced hypertension and polyhydramnios ameliorated before C-section was performed two weeks later and unrelated to the intervention. This case report underlines the importance of early diagnosis and treatment of primary hyperparathyroidism during pregnancy. If diagnosed in the third trimenon, an interdisciplinary approach is crucial. If medical treatment fails to sufficiently control hypercalcemia, surgical parathyroid exploration should be considered even in cases of unsuccessful localization of adenomatous parathyroid glands.