Interpreting epigenetic causes of recurrent hypokalemia and seizures: Gitelman syndrome co-exist with pseudohypoparathyroidism type 1B.

We describe a unique case of 27-year-old male with Gitelman syndrome (GS) co-exist with pseudohypoparathyroidism type 1B (PHP1B). The patient presented with a 5-year history of seizures, tetany, and numbness of the extremities. Further examinations showed recurrent hypokalemia, inappropriate kaliuresis, hypocalcemia, hyperphosphatemia, and elevated PTH levels. A novel variant of autosomal recessive GS (p.Val287Met SLC12A3) and a novel 492.3Kb deletion containing the whole of STX16, were discovered by a whole-exome sequencing. Following the diagnosis, calcitriol, calcium, and potassium supplements were started. Hematuria calcium and phosphorus levels, as well as blood potassium levels, have recovered and remained within normal ranges after 3 years of follow-up. Our findings have important consequences for supporting the idea that heterozygosity for variants have effects on the patients' clinical performance with autosomal recessive inheritance disorders. Further study is need for the putative effects of the variant. Likewise, further investigation with regards to the gene-gene interaction relations between GS and other electrolyte imbalance disorders is warranted.

A Case of Pseudohypoparathyroidism Misdiagnosed as Idiopathic Epilepsy for 5 Years: Clinical Analysis and Follow-up Outcomes.

We report a 15-year-old Chinese girl who presented with intermittent seizure episodes and had been misdiagnosed as having idiopathic epilepsy 5 years previously. Laboratory testing revealed hypocalcemia, hyperphosphatemia, and a high parathyroid hormone (PTH) concentration. She was subsequently shown to have pseudohypoparathyroidism type Ib (PHPIb) based on the results of methylation analysis of the GNAS gene, which showed a loss of methylation of the differentially methylated regions (DMR) of GNAS-AS1, GNAS-XL, and GNAS-A/B; and a gain of methylation of the DMR of the GNAS-NESP55 region. We adjusted the patient's medication by prescribing calcium and calcitriol supplements, and gradually reduced the doses of antiepileptic drugs, until they had been completely discontinued. As a result, the patient did not experience any further seizures or epileptiform symptoms; and had normal plasma calcium, phosphorus, and 25-hydroxyvitamin D concentrations and 24-hour urinary calcium excretion. In addition, her PTH concentration gradually normalized over 12 months, and no urinary stones were found on ultrasonographic examination. In conclusion, the clinical presentation of PHP is complex, and the condition is often misdiagnosed. The diagnosis and follow-up of the present patient have provide valuable insights that should contribute to informed clinical decision-making and the implementation of appropriate treatment strategies.

Parathyroid Hormone Resistance: An Uncommon Cause of Hypocalcaemia in an Adult Ghanaian Female.

BACKGROUND AND OBJECTIVE: Parathyroid hormone (PTH) resistance, the main biochemical feature of a rare group of disorders known as Pseudohypoparathyroidism (PHP) is an uncommon cause of hypocalcaemia. In addition to the biochemical abnormalities, some individuals with PHP may have features of Albright Hereditary Osteodystrophy (AHO). Being a rare disorder with a significant level of variation and overlap in its clinical presentation, diagnosis of PHP may be challenging in some clinical settings. This case report highlights the diagnosis of this rare disorder. CASE REPORT: A 20-year-old Ghanaian female who had been involved in a road traffic accident (RTA) was referred to the endocrine clinic after a computer tomography (CT) scan of her head revealed an incidental finding of multiple basal ganglia calcifications. Investigations revealed hypocalcaemia, hyperphosphatemia, and elevated intact PTH in the presence of normal levels of 25-hydroxyvitamin D and magnesium, and a normal kidney function. She also had phenotypic features of AHO. Findings suggested a diagnosis of PHP, however, the type could not be identified due to the unavailability of further testing. CONCLUSION: This report of a Ghanaian female with PTH resistance and features of AHO diagnosed at the age of 20 years, is expected to add to the existing literature and assist in increasing the level of awareness and facilitate the diagnosis of this disorder in our setting.

CONTEXTE ET OBJECTIF: La résistance à l'hormone parathyroïdienne (PTH), principale caractéristique biochimique d'un groupe rare de troubles connus sous le nom de pseudohypoparathyroïdie (PHP), est une cause rare d'hypocalcémie. En plus des anomalies biochimiques, certaines personnes atteintes de PHP peuvent présenter des caractéristiques d'ostéodystrophie héréditaire d'Albright (AHO). Étant un trouble rare avec un niveau significatif de variation et de chevauchement dans sa présentation clinique, le diagnostic de PHP peut être difficile dans certains contextes cliniques. Ce rapport de cas met en lumière le diagnostic de cette maladie rare. RAPPORT DE CAS: Une femme ghanéenne de 20 ans qui avait été impliquée dans un accident de la circulation routière (RTA) a été référée à la clinique endocrinienne après qu'une tomodensitométrie (TDM) de sa tête a révélé la découverte fortuite de multiples calcifications des ganglions de la base. Les examens ont révélé une hypocalcémie, une hyperphosphatémie et une PTH intacte élevée en présence de taux normaux de 25 hydroxyvitamine D et de magnésium et d'une fonction rénale normale. Elle avait également des caractéristiques phénotypiques d'AHO. La découverte a suggéré un diagnostic de PHP, mais le type n'a pas pu être identifié en raison de l'indisponibilité de tests supplémentaires. CONCLUSION: Ce rapport d'une femme ghanéenne présentant une résistance à la PTH et des caractéristiques d'AHO diagnostiquée à l'âge de 20 ans, devrait s'ajouter à la littérature existante et aider à accroître le niveau de sensibilisation et à faciliter le diagnostic de ce trouble dans notre contexte. Mots-clés: Hypocalcémie, Hormone parathyroïdienne, Ghana.

Application of calcium-to-phosphorus (Ca/P) ratio in the diagnosis of pseudohypoparathyroidism: another piece in the puzzle of diagnosis of Ca-P metabolism disorders.

Objective: The serum calcium (Ca)-to-phosphorus (P) ratio has been proposed to identify patients with primary hyperparathyroidism and chronic hypoparathyroidism (HPT), but it has never been tested in pseudohypoparathyroidism (PHP). The aim of this study was to test the performance of Ca/P ratio in PHP diagnosis compared with that in healthy subjects and patients with HPT for differential diagnosis. Design: A retrospective, cross-sectional, and observational study was carried out. Methods: Serum Ca, P, creatinine, parathyroid hormone (PTH), and albumin were collected. Ca and P were expressed in mmol/L. Ca/P diagnostic performance was evaluated by receiver operating characteristic curve, sensitivity, specificity, and accuracy. Results: A total of 60 patients with PHP, 60 patients with HPT, and 120 controls were enrolled. The Ca/P ratio was lower in patients with PHP and HPT than that in controls (p < 0.0001). The cutoff of 1.78 (2.32 if Ca and P measured in mg/dL) for Ca/P ratio could identify patients with PHP and HPT among the entire cohort (sensitivity and specificity of 76%). No valid cutoff of Ca/P was found to distinguish patients with PHP from patients with HPT; in this case, PTH above 53.0 ng/dL identified patients with PHP (sensitivity and specificity of 100%). The index (Ca/P × PTH) above 116 ng/L recognized patients with PHP from controls (sensitivity of 84.7% and specificity of 87.4%), whereas (Ca/P × PTH) below 34 ng/L recognized patients with HPT from controls (sensitivity of 88.9% and specificity of 90.8%). Conclusions: The Ca/P ratio below 1.78 (2.32 CU) is highly accurate to identify patients with PHP and HPT, although it is not reliable to differentiate these two conditions. The index (Ca/P × PTH) is excellent to specifically recognize PHP or HPT from healthy subjects.

Nutrition recommendations for patients with pseudohypoparathyroidism.

Pseudohypoparathyroidism (PHP) is a spectrum of diseases characterized by insensitivity of target tissues to the action of parathyroid hormone and, consequently, by the presence of hyperphosphatemia and hypocalcaemia of varying severity. Early-onset obesity is a feature of PHP type 1A. This article discusses the need to establish uniform criteria to guide the nutritional management of patients with PHP. A decrease in energy expenditure calls for an adjustment of the energy content of the diet. Reducing the intake of foods rich in inorganic phosphorus helps to manage hyperphosphataemia. Targeted nutrition should be part of the treatment plan of children and adolescents with PHP, since it contributes to modulating the calcium and phosphorus metabolism imbalances characteristic of these patients.

Clinical and genetic characteristics for 4 patients with Type Ib pseudohypoparathyroidism. / 4例Ibåž‹å‡æ€§ç”²çŠ¶æ—è ºåŠŸèƒ½å‡é€€ç—‡çš„ä¸´åºŠå’Œé—ä¼ å­¦ç‰¹å¾.

Pseudohypoparayhyroidism (PHP) is a rare autosomal dominant or recessive genetic disorder characterized by low calcium, high phosphorus, and target organ resistance to parathyroid. The clinical characteristics and genetic features in 4 patients with Type Ib PHP in the Third Xiangya Hospital, Central South University, have been reviewed. All 4 patients had low calcium, high phosphorus, and parathyroid resistance. Among them, 2 patients had slightly elevated thyroid stimulating hormone and mild features of Albright's hereditary osteodystrophy, and one patient had hypokalemia. No guanine nucleotide-binding protein alpha-stimulating activity polypeptide 1 (GNAS) and gene variant associated with hypokalemia were identified using the whole exome sequencing. The results of the methylation-specific multiple ligation-dependent probe amplification showed that there were abnormal methylation of the upstream differentially methylated regions of GNAS in the 4 patients. There were phenotype overlap among the various subtypes of PHP. Detection of GNAS gene methylation in patients with clinical suspicion of Type Ib PHP is helpful for the diagnosis and treatment of PHP.

Clinical and genetic analysis of pseudohypoparathyroidism complicated by hypokalemia: a case report and review of the literature.

BACKGROUND: Pseudohypoparathyroidism (PHP) encompasses a highly heterogenous group of disorders, characterized by parathyroid hormone (PTH) resistance caused by mutations in the GNAS gene or other upstream targets. Here, we investigate the characteristics of a female patient diagnosed with PHP complicated with hypokalemia, and her family members. CASE PRESENTATION AND GENE ANALYSIS: A 27-year-old female patient occasionally exhibited asymptomatic hypocalcemia and hypokalemia during her pregnancy 1 year ago. Seven months after delivery, she experienced tetany and dysphonia with diarrhea. Tetany symptoms were relieved after intravenous calcium gluconate supplementation and she was then transferred to our Hospital. Laboratory assessments of the patient revealed hypokalemia, hypocalcemia and hyperphosphatemia despite elevated PTH levels. CT scanning of the brain revealed globus pallidus calcification. Possible mutations in GNAS and hypokalemia related genes were identified using WES, exon copies of STX16 were analized by MLPA and the methylation status of GNAS in three differential methylated regions (DMRs) was analyzed by methylation-specific polymerase chain reaction, followed by confirmation with gene sequencing. The patient was clinically diagnosed with PHP-1b. Loss of methylation in the A/B region and hypermethylation in the NESP55 region were detected. No other mutations in GNAS or hypokalemia related genes and no deletions of STX16 exons were detected. A negative family history and abnormal DMRs in GNAS led to a diagnosis of sporadic PHP-1b of the patient. CONCLUSIONS: Hypokalemia is a rare disorder associated with PHP-1b. Analysis of genetic and epigenetic mutations can aid in the diagnosis and accurate subtyping of PHP.

An intricate case of sporadic pseudohypoparathyroidism type 1B with a review of literature

SUMMARY Pseudohypoparathyroidism comprehends an assorted group of genetically rare disorders that share end-organ resistance to parathyroid hormone. Genetic and epigenetic modifications on guanine nucleotide-binding protein alpha-stimulating gene locus are the most common underlying mechanisms associated with pseudohypoparathyroidism. Biochemical and molecular analysis stratify pseudohypoparathyroidism into types 1A, 1B, 1C, and 2. We describe an unusual case of sporadic pseudohypoparathyroidism type 1B. A 34-year-old Caucasian woman was admitted to the emergency department, with persistent asthenia, limb paresthesias, and tactile hyposensitivity. Her physical examination, previous personal and family histories were unsuspicious, except for mild, intermittent and self-limited complaints of paresthesia during her two pregnancies, but no detailed workup was done. No typical features of Albright hereditary osteodystrophy were observed. The initial laboratory investigation showed elevated parathyroid hormone level (311.2 pg/mL), hypocalcemia (albumin-corrected serum calcium 4.3 mg/dL), hypocalciuria, hyperphosphatemia, hypophosphaturia, and vitamin D deficiency. Combined calcium, vitamin D, and magnesium supplementation was commenced, with symptomatic and analytical improvement. Albeit resolution of vitamin D deficiency, the patient relapsed with mild and intermittent lower limb paresthesias. Pseudohypoparathyroidism was confirmed by molecular identification of the 3-kb STX16 deletion. The treatment was readjusted, and one year later, symptomatic remission was attained. Clinical and biochemical features, and their respective course, along with lack of distinctive features of Albright hereditary osteodystrophy pointed to pseudohypoparathyroidism type 1B. A careful follow-up is needed to avoid complications and recurrence. Once correction of hypocalcemia and hyperphosphatemia is achieved, with no reported complications and recurrence, a good prognosis is anticipated, comparable to the general population.

A novel GNAS mutation in pseudohypoparathyroidism type 1a in a Chinese man presented with recurrent seizure: a case report.

BACKGROUND: Pseudohypoparathyroidism is a rare genetic disease characterized by hypocalcaemia and hyperphosphataemia due to the defect to the guanine nucleotide-binding protein alpha subunit (GNAS) gene. Patients with pseudoparathyroidism type 1a and 1c could manifest Albright's hereditary osteodystrophy and multiple hormone resistance including gonadotropin and thyroid stimulating hormone. CASE PRESENTATION: Here we report a Chinese man who presented with fatigue, recurrent seizure and Albright's hereditary osteodystrophy. His genetic study revealed a heterozygote mutation in the GNAS gene [NM_000516.4(GNAS): c2787_2788del (p.Val930AspfsTer12)]. After calcium and calcitriol supplement, his seizures achieved partially remission. CONCLUSIONS: We report a case of PHP1a or 1c with a novel frameshift mutation in GNAS gene in a patient presenting with AHO, as well as TSH and partial gonadotropin resistance. This mutation in this case has not been reported in literature and adds to the spectrum of genetic mutations related to PHP.

An intricate case of sporadic pseudohypoparathyroidism type 1B with a review of literature.

Pseudohypoparathyroidism comprehends an assorted group of genetically rare disorders that share end-organ resistance to parathyroid hormone. Genetic and epigenetic modifications on guanine nucleotide-binding protein alpha-stimulating gene locus are the most common underlying mechanisms associated with pseudohypoparathyroidism. Biochemical and molecular analysis stratify pseudohypoparathyroidism into types 1A, 1B, 1C, and 2. We describe an unusual case of sporadic pseudohypoparathyroidism type 1B. A 34-year-old Caucasian woman was admitted to the emergency department, with persistent asthenia, limb paresthesias, and tactile hyposensitivity. Her physical examination, previous personal and family histories were unsuspicious, except for mild, intermittent and self-limited complaints of paresthesia during her two pregnancies, but no detailed workup was done. No typical features of Albright hereditary osteodystrophy were observed. The initial laboratory investigation showed elevated parathyroid hormone level (311.2 pg/mL), hypocalcemia (albumin-corrected serum calcium 4.3 mg/dL), hypocalciuria, hyperphosphatemia, hypophosphaturia, and vitamin D deficiency. Combined calcium, vitamin D, and magnesium supplementation was commenced, with symptomatic and analytical improvement. Albeit resolution of vitamin D deficiency, the patient relapsed with mild and intermittent lower limb paresthesias. Pseudohypoparathyroidism was confirmed by molecular identification of the 3-kb STX16 deletion. The treatment was readjusted, and one year later, symptomatic remission was attained. Clinical and biochemical features, and their respective course, along with lack of distinctive features of Albright hereditary osteodystrophy pointed to pseudohypoparathyroidism type 1B. A careful follow-up is needed to avoid complications and recurrence. Once correction of hypocalcemia and hyperphosphatemia is achieved, with no reported complications and recurrence, a good prognosis is anticipated, comparable to the general population.

A patient with extensive cerebral calcification due to pseudohypoparathyroidism: a case report.

BACKGROUND: Pseudohypoparathyroidism(PHP) is a heterogeneous group of disorders due to impaired activation of c AMP dependant pathways following binding of parathyroid hormone (PTH) to its receptor. In PHP end organ resistance to PTH results in hypocalcaemia, hyperphosphataemia and high PTH levels. CASE PRESENTATION: A 59 year old male presented with a history of progressive impairment of speech and unsteadiness of gait for 1 week and acute onset altered behavior for 1 day and one episode of generalized seizure. His muscle power was grade four according to MRC (medical research council) scale in all limbs and Chovstek's and Trousseau's signs were positive. Urgent non contrast computed tomography scan of the brain revealed extensive bilateral cerebral and cerebellar calcifications. A markedly low ionized calcium level of 0.5 mmol/l, an elevated phosphate level of 9.5 mg/dl (reference range: 2.7-4.5 mg/dl) and an elevated intact PTH of 76.3 pg/l were noted. His renal functions were normal. His hypocalcemia was accentuated by the presence of hypomagnesaemia. His 25 hydroxy vitamin D level was only marginally low which could not account for severe hypocalcaemia. A diagnosis of pseudohypoparathyroidism without phenotypic defects, was made due to hypocalcaemia and increased parathyroid hormone levels with cerebral calcifications. The patient was treated initially with parenteral calcium which was later converted to oral calcium supplements. His coexisting Vitamin D deficiency was corrected with 1αcholecalciferol escalating doses. His hypomagnesaemia was corrected with magnesium sulphate parenteral infusions initially and later with oral preparations. With treatment there was a significant clinical and biochemical response. CONCLUSION: Pseudohypoparathyroidism can present for the first time in elderly resulting in extensive cerebral calcifications. Identification and early correction of the deficit will result in both symptomatic and biochemical response.

A typical 22q11.2 deletion syndrome and pseudohypoparathyroidism: A CARE compliant case report.

RATIONALE: It is rare to find 22q11.2 deletion syndrome with pseudohypoparathyroidism in children. Furthermore, the phenotypic spectrum of this disorder varies widely. PATIENT CONCERNS: A patient was diagnosed with pseudohypoparathyroidism at age 14 years because of convulsions, hypocalcemia, hyperphosphatemia, normal parathyroid hormone levels, and basal ganglia calcifications. Thereafter, the child presented with symptoms of nephrotic syndrome; subsequently, he was diagnosed with nephrotic syndrome at the local hospital. DIAGNOSIS: At our hospital, multiplex ligation-dependent probe amplification confirmed that the patient had 22q11.2 deletion syndrome. INTERVENTIONS: The patient continued to be treated with calcium supplements. OUTCOMES: Seizure activity and proteinuria ceased. LESSONS: Signs of this syndrome include delayed speech development due to velofacial dysfunction, recurrent croup attacks during early childhood due to latent hypocalcemia, and mild dysmorphic features. The findings of this patient indicated that 22q11.2 deletion syndrome may include a wide spectrum of clinical findings and that this diagnosis needs to be considered for all patients presenting with hypocalcemia, regardless of age.

Cardiovascular findings in patients with nonsurgical hypoparathyroidism and pseudohypoparathyroidism: A cohort study.

OBJECTIVE: As only sparse data are available on indices of cardiovascular health among patients with nonsurgical hypoparathyroidism (Ns-HypoPT) and pseudohypoparathyroidism (PHP), we aimed to compare the cardiovascular profile between these groups of patients. METHODS: A total of 56 patients with Ns-HypoPT and 30 with PHP were included and underwent a clinical examination including blood sampling and measurements of arterial stiffness, pulse wave velocity (PWV) and blood pressure (BP). Arterial stiffness and PWV were measured using AtCor SphygmoCor-XCEL (Atcor Medical Pty Ltd, Sydney, NSW, Australia). RESULTS: Patients with Ns-HypoPT had an average age of 47 ± 17 years (68% females) and PHP patients 36 ± 13 years (80% females). Over 70% in both groups were genetically screened. Groups did not differ in terms of a history of cardiovascular disease, smoking status, use of calcium and vitamin D supplements or treatment with cholesterol-lowering or antihypertensive drugs. Compared with Ns-HypoPT, PHP patients had significantly lower levels of high-density lipoproteins (HDL) cholesterol and average glucose from HbA1c (Pboth  = 0.01). PWV was significantly higher among patients with Ns-HypoPT (Pcrude  = 0.02), even after adjustment for mean arterial pressure, body mass index, age and gender (Padjusted  < 0.01). Heart rate was significantly higher in Ns-HypoPT compared with PHP (P = 0.03). Office BP and 24-hour ambulatory BP did not differ between groups (P > 0.05). CONCLUSION: Patients with Ns-HypoPT have compared with PHP a higher arterial stiffness and heart rate. This has been associated with an increased risk of cardiovascular disease. Our data suggest that resistance to PTH is present in the cardiovascular system in PHP.

Renal Tubular Dysfunction Fully Accounts for Plasma Biochemical Abnormalities in Type 1A Pseudohypoparathyroidism.

Context: Type 1A pseudohypoparathyroidism (PHP-1A) is characterized by target organ resistance to PTH. Patients can present with various dysmorphic features; however, renal failure has not been classically described. Case Description: A female patient came to our attention at the age of 7 years with characteristic signs of PTH resistance (i.e., hypocalcemia, hyperphosphatemia, and high serum PTH levels). She also presented with hypothyroidism, early-onset obesity, short metacarpal bones, and multiple subcutaneous ossifications, leading to a clinical diagnosis of pseudohypoparathyroidism. In addition to her genetic condition, she had bilateral renal hypodysplasia that was slowly progressing to end-stage kidney disease. She received a kidney transplant at the age of 16 years and, after transplantation, experienced rapidly normalized calcium, phosphate, and PTH levels, allowing f withdrawal of vitamin D supplementation. Conclusions: To the best of our knowledge, ours is the first report of a patient with PHP-1A undergoing kidney transplantation. Normalization of biochemical parameters after the procedure demonstrated that renal tubular resistance to PTH is sufficient to explain the calcium/phosphate abnormalities observed in PHP-1A.

Neonatal transient pseudohypoparathyroidism: could it be included among inactivating parathyroid hormone (PTH)/PTH-related protein signalling disorders?

We report a case of transient pseudohypoparathyroidism in a full-term newborn that presented at 20 hours of life with hypocalcemic seizures, hyperphosphatemia and raised parathormone levels. The diagnosis of pseudohypoparathyroidism was made according to biochemical investigations. The infant was treated with calcium supplementation and vitamin D analog therapy, and he remained stable and symptom-free with normal serum biochemistries during follow-up. We suggest that transient pseudohypoparathyroidism of the newborn (ntPHP) might be included among inactivating parathyroid hormone (PTH)/PTH-related protein signaling disorders as defined by the classification schema recently proposed by the European Pseudohypoparathyroidism Network. To the best of our knowledge, this is the first report in which the new classification has been applied to a case of ntPHP.

Pseudohypoparathyroidism with basal ganglia calcification: A case report of rare cause of reversible parkinsonism.

RATIONALE: Parkinsonism can be secondary to many internal diseases, in some certain conditions, it seems that the clinical manifestations of parkinsonism presenting reversible. We report a case of patient with parkinsonism secondary to pseudohypoparathyroidism, who improved markedly after the supplement of serum calcium. PATIENT CONCERNS AND DIAGNOSES: A 52-year-old woman with acute parkinsonism was diagnosed as pseudohypoparathyroidism after the conducting of brain computed tomography, laboratory examinations, and gene detection. The son of the patient was also examined and was diagnosed as pseudohypoparathyroidism, who had ever complained of the history of epilepsy. The clinical manifestations of parkinsonism of the patient was reevaluated after the supplement of serum calcium according to the diagnosis. INTERVENTIONS AND OUTCOMES: The brain computed tomography revealed the basal ganglia calcification of the patient, accompanying by serum hypocalcemia and hyperphosphatemia. Loss of function mutation also confirmed the diagnosis. Five days after the therapy targeting at correction of serum hypocalcemia, the patient improved greatly in dyskinesia. LESSONS: This study reported a patient presenting as acute reversible parkinsonism, who was finally diagnosed as pseudohypoparathyroidism. It indicated us that secondary parkinsonism should be carefully differentiated for its dramatic treatment effect. And the family history of seizures might be an indicator for the consideration of pseudohypoparathyroidism.

Cinacalcet as adjunctive therapy in pseudohypoparathyroidism type 1b.

BACKGROUND: In patients with pseudohypoparathyroidism type 1b (PHP1b) due to a tissue-specific imprinting defect in the G-protein α-subunit, skeletal disorders can arise from the bones being sensitive to parathyroid hormone (PTH) while the kidneys remain resistant to this hormone. CASE-DIAGNOSIS/TREATMENT: We report a 4.8-year-old girl with PHP1b who presented with an abnormal gait, severe skeletal changes and elevated levels of serum PTH (2844 pg/ml), phosphate (7.2 mg/dl) and bone turnover markers. Traditional treatment with calcium and calcitriol failed to suppress PTH secretion, which was still elevated at 2877 pg/ml after 14 months of therapy, nor did it correct the other clinical, biochemical and radiographic abnormalities. The addition of cinacalcet to the treatment regimen over the subsequent 32 months resulted in normalization of serum PTH (58 ng/ml), phosphate (4.9 mg/dl) and bone turnover markers, and resolution of the radiographic changes, with no adverse effects noted. CONCLUSIONS: Due to its ease of administration, we recommend the addition of cinacalcet into the armamentarium of medications available to treat children with PHP1b.