Parathyroid carcinoma: Report of 10 patients and literature review.

OBJECTIVE: Parathyroid carcinoma (PC) is a rare disease with high rates of misdiagnosis and recurrence. This report summarized the clinical and pathological characteristics of 10 patients with PC at our hospital, to improve the early recognition and prognosis of PC. METHODS: The clinical manifestations, imaging findings, pathological features, treatments, and prognostic data of 10 patients diagnosed with PC at the First Medical Center, Chinese PLA General Hospital from 2003 to 2021 were analyzed. RESULTS: There were 7 male and 3 female patients with PC whose average age was 41.4 ± 9.4 years. All patients had bone involvement (bone pain and/or osteoporosis), meanwhile 6 patients had kidney stones and 7 patients had palpable neck masses. Five patients presented with tumor metastasis, invading lymph nodes, lung, liver, or bone. Laboratory examinations revealed elevated serum total calcium (4.15 ± 0.81 mmol/L), parathyroid hormone (PTH, 1236.1 ± 519.9 pg/mL) and alkaline phosphatase (405.8 ± 219.0 IU/L) levels. Especially, hypercalcemic crisis occurred in 9 patients. The diagnosis of PC depended on histopathological features of the parathyroid tumor, including capsular and/or vascular invasion. All patients underwent at least en bloc resection. In the follow-up, six patients with relatively high preoperative PTH levels (1519.5 ± 436.8 pg/mL) relapsed postoperatively. Two patients with the Ki-67 index ≥ 10% in parathyroid tumor tissue and distant metastasis died within 2 years after the operation. CONCLUSION: Severe bone pain, kidney stones, hypercalcemic crisis, and markedly elevated PTH usually indicate PC. A markedly elevated PTH level, tumor metastasis, and the Ki-67 index ≥ 10% may be indicators of poor prognosis.

Clinical data analysis of 22 cases with hypoparathyroidism misdiagnosed as epilepsy.

OBJECTIVE: Patients with hypoparathyroidism always present with recurrent tetany caused by hypocalcemia. These patients are usually misdiagnosed with epilepsy and incorrectly treated with anti-epileptic drugs. This research analyzed clinical data about 22 patients with hypoparathyroidism misdiagnosed as epilepsy and summarized the clinical experience for reducing misdiagnosis and incorrect therapy about hypoparathyroidism. METHOD: Totally 160 patients with hypoparathyroidism, administrated to the First Medical Center of Chinese PLA General Hospital from January 1st, 2008, to July 1st, 2021, were enrolled in this report. Clinical data about 22 patients initially misdiagnosed with epilepsy were analyzed. RESULTS: Of the 160 cases with hypoparathyroidism, 22 patients (12 males and 10 females) were misdiagnosed with epilepsy in local hospitals. The misdiagnosis rate was 13.75% and the median duration of misdiagnosis was 8.0 (2.0, 14.8) years. The clinical manifestations of the 22 patients misdiagnosed as epilepsy included tetany 81.8% (18/22), disturbance of consciousness 27.3% (6/22), limb numbness 13.6% (3/22), limb weakness 27.3% (6/22), mental and behavioral abnormality 9.1% (2/22), and memory impairment 13.6% (3/22), etc. Electroencephalogram (EEG) was performed in 9 cases, which presented as slow wave and spike-slow complex wave in 3 cases, slowing down of Î¸ and δ band background in 2 cases and normal EEG in 4 cases. Out of the 15 cases that underwent head computed tomography (CT) scan, in which 13 cases had intracranial calcification. Anti-epileptic drugs were used to treat 22 patients, of which 17 patients were treated with two kinds of drugs. With calcium and calcitriol supplement in all these 22 patients, the anti-epileptic drugs were gradually reduced and withdrawn in 17 cases. In the other 5 cases with secondary epilepsy, the type of anti-epileptic drugs was reduced to one and the clinical condition improved obviously. CONCLUSION: The clinical manifestations of hypoparathyroidism are complex and usually be misdiagnosed as primary epilepsy. Detection of serum calcium, phosphorus and parathyroid hormone is very important to avoid misdiagnosis and incorrect therapy about hypoparathyroidism.

Insulinoma misdiagnosed as epilepsy in 44 Chinese patients.

OBJECTIVE: Insulinoma is a rare pancreatic neuroendocrine tumor that can spontaneously produce excess endogenous insulin, resulting in recurrent and serious hypoglycemia. Patients with insulinoma always have intermittent neuroglycopenia, which has been frequently reported as being misdiagnosed as epilepsy. In this report, we analyzed the clinical data of patients with confirmed insulinoma who had ever been misdiagnosed to have epilepsy. METHODS: The retrospective review was performed on 266 patients with confirmed insulinoma at the First Medical Center of Chinese PLA General Hospital between January 2000 and July 2020. RESULTS: 1. The diagnosis of insulinoma was confirmed in 266 patients. Forty-four patients [male/female=1/1.8, aged (41.25±12.30) years old] were misdiagnosed to have epilepsy, with a misdiagnosis rate of 16.5%. 2. Thirty-eight patients presented with consciousness disorder. Eleven patients presented with palpitation, sweating, and anxiety. Five patients presented with convulsion and 6 patients presented with abnormal behavior and delirium. 3. Twenty-two patients underwent EEG examination. EEG showed spike wave or spike-slow complex wave in 5 patients, decreased α wave and increased slow wave in θ and δ band in 7 patients, and was normal in 10 patients. 4. Thirty-five patients were incorrectly prescribed with AEDs and 22 patients were even misdiagnosed to have refractory epilepsy. 5. All these 44 patients underwent successful surgery, and hypoglycemia symptoms were relieved after insulinoma resection. CONCLUSION: Patients with insulinoma sometimes share common clinical characteristics with epilepsy. To patients with epilepsy or suspected epilepsy, especially with poor response to ADEs, hypoglycemia caused by insulinoma should be emphasized in the differential diagnosis.

Paget's disease of bone: Report of 11 cases.

BACKGROUND: Paget's disease of bone (PDB) is a rare metabolic bone disease in China and is characterized by increased bone resorption and disorganized bone formation. The main clinical symptoms of PDB are focal or multiple bone pain and deformity with high disability. The disease has high missed diagnosis and misdiagnosis rates. This report summarizes the clinical manifestations, imaging and pathological features, and treatments of 11 patients with PDB at our hospital from 1993 to 2020 in order to improve the recognition and prognosis of PDB. CASE SUMMARY: There were eight male and three female patients whose average age was 48.7 ± 11.0 years with a PDB course of 1-16 years. Nine patients had bone pain and bone deformities in different parts of the body, the majority of which involved the long bones. Laboratory examinations revealed elevated serum alkaline phosphatase (ALP) in all patients with an average of 618 ± 460 IU/L (normal range 0-130 IU/L), and serum calcium and phosphorus levels were in the normal range. Imageology showed that osteolysis was usually combined with osteosclerosis and/or bone deformities in single or multiple bones. 99mTc-methylene diphosphonate bone scintigraphy revealed increased radionuclide uptake in the bone lesions. Six patients underwent bone tissue biopsy, and the typical pathological changes were a mosaic structure of the bone trabeculae with irregularly arranged cement lines and multinuclear osteoclasts. Ten of the 11 patients were effectively treated with bisphosphonates. CONCLUSION: Early diagnosis of the rare disease PDB can be made through elevated ALP levels and typical presentations on bone X-ray and from bone tissue biopsy.

Bilateral adrenocortical adenomas causing adrenocorticotropic hormone-independent Cushing's syndrome: A case report and review of the literature.

BACKGROUND: Adrenocorticotropic hormone (ACTH)-independent Cushing's syndrome (CS) is mostly due to unilateral tumors, with bilateral tumors rarely reported. Its common causes include primary pigmented nodular adrenocortical disease, ACTH-independent macronodular adrenal hyperplasia, and bilateral adrenocortical adenomas (BAAs) or carcinomas. BAAs causing ACTH-independent CS are rare; up to now, fewer than 40 BAA cases have been reported. The accurate diagnosis and evaluation of BAAs are critical for determining optimal treatment options. Adrenal vein sampling (AVS) is a good way to diagnose ACTH-independent CS. CASE SUMMARY: A 31-year-old woman had a typical appearance of CS. The oral glucose tolerance test showed impaired glucose tolerance and obviously increased insulin and C-peptide levels. Her baseline serum cortisol and urine free cortisol were elevated and did not show either a circadian rhythm or suppression with dexamethasone administration. The peripheral 1-deamino-8-D-arginine-vasopressin (DDVAP) stimulation test showed a delay of the peak level, which was 1.05 times as high as the baseline level. Bilateral AVS results suggested the possibility of BAAs. Abdominal computed tomography showed bilateral adrenal adenomas with atrophic adrenal glands (right: 3.1 cm × 2.0 cm × 1.9 cm; left: 2.2 cm × 1.9 cm × 2.1 cm). Magnetic resonance imaging of the pituitary gland demonstrated normal findings. A left adenomectomy by retroperitoneoscopy was performed first, followed by resection of the right-side adrenal mass 3 mo later. Biopsy results of both adenomas showed cortical tumors. Evaluations of ACTH and cortisol showed a significant decrease after left adenomectomy but could still not be suppressed, and the circadian rhythm was absent. Following bilateral adenomectomy, this patient has been administered with prednisone until now, all of her symptoms were alleviated, and she had normal blood pressure without edema in either of her lower extremities. CONCLUSION: BAAs causing ACTH-independent CS are rare. AVS is of great significance for obtaining information on the functional state of BAAs before surgery.

Thyrotrophic status in patients with pituitary stalk interruption syndrome.

Pituitary stalk interruption syndrome (PSIS) is associated with simultaneous or subsequent pituitary hormone deficiencies (PHDs). Although the clinical features of multiple PHDs are well known, the status of the thyrotrophic axis in PSIS has not been thoroughly investigated.The clinical data of 89 PSIS patients and 34 Sheehan syndrome (SS) patients were retrospectively analyzed.The prevalence of central hypothyroidism in the PSIS patients and the SS patients was 79.8% and 70.6%, respectively. The thyroid-stimulating hormone (TSH) levels in the PSIS patients were significantly higher in comparison with the SS patients (5.13 ±â€Š3.40 vs 1.67 ±â€Š1.20 mU/L, P < .05). TSH elevation (8.79 ±â€Š3.17 mU/L) was noticed in 29 of 71 (40.85%) hypothyroid PSIS patients but not in the 24 hypothyroid SS patients. The TSH levels in the hypothyroid PSIS patients were significantly higher in comparison with the euthyroid PSIS patients (5.42 ±â€Š3.67 vs 3.66 ±â€Š1.50 mU/L). Thyroid hormone replacement significantly reduced the TSH levels in the PSIS patients with elevated TSH levels from 7.24 ±â€Š0.98 to 1.67 ±â€Š1.51 mU/L (P < .05). The logistic regression analysis suggested that TSH level was not significantly associated with pituitary stalk status and height of the anterior pituitary gland.PSIS is a newly recognized cause of central hypothyroidism. The proportion and amplitude of TSH elevations are higher in PSIS than in other causes of central hypothyroidism.

Whole-genome sequencing revealed armadillo repeat containing 5 (ARMC5) mutation in a Chinese family with ACTH-independent macronodular adrenal hyperplasia.

Primary macronodular adrenal hyperplasia (PMAH), also known in the past as bilateral macronodular adrenalhyperplasia or adrenocorticotropin (ACTH)-independent macronodular adrenal hyperplasia, is a rare type of Cushing's syndrome (CS) and is associated with bilateralenlargement of the adrenal glands. It accounts for <1% of all endogenous cases of CS. In order toidentify the pathogenic mutations in the causative gene of (AIMAH pedigrees, Whole-genome sequencing of three patients in family I was used to retrieve candidate causative genes. Meanwhile, the causative gene was identified by Sanger sequencing from the two pedigrees. Sequencing of ARMC5 exons of three patients was carried out to identify somatic mutations. Moreover, haploid clone of one tumor DNA sample was conducted. ARMC5 was the causative gene of two pedigrees confirmed by whole-genome sequencing (WGA) and Sanger sequencing. The variant sites of the two families were c.C943T (p.R315W) and c.C1960T (p.R654X), respectively. Autosomal dominant inheritance of AIMAH was confirmed by genotypes of one family member. Several somatic mutations were discovered in tumor DNA samples. In addition, haploid clone of tumor DNA was confirmed by germline mutation and somaticmutation, which suggested the pathogenic mechanism of "two-hit-model." ARMC5 was the causative gene of AIMAH pedigrees. This AIMAH in this study presented autosomal dominant inheritance, fitting to Mendelian inheritance law. However, the pathogenic mode of this disease showed as compound heterozygote.

Dynamic profile of differentiated thyroid cancer in male and female patients with thyroidectomy during 2000-2013 in China: a retrospective study.

The study aimed to investigate the gender-related differences of disease onset, age distribution, blood type, clinical characteristics, and malignant behaviors of differentiated thyroid carcinoma (DTC) in Chinese patients. A total of 7385 consecutive thyroid cancer patients who underwent thyroidectomy were retrospectively reviewed. 4087 (55.3%) were diagnosed as benign and the other (3298, 44.7%) were as malignant. DTC accounted for 97.6% in the malignant tumor. More single nodules turned out to be DTC in male compared to multiple nodules (46.9% vs. 40.4%, P = 0.004). The proportion increased along with the increase of year during 2000-2013, which was from 7.5% to 68.1% in males and from 16.2% to 66.7% in females. The level of preoperative TSH was significantly higher in patients with DTC compared to the patients with benign (1.97 vs. 1.57 mIU/L, P < 0.001). The proportion of thyroid cancer was dominated in blood type B and the lowest incidence in blood type A in male, the difference was not statistically significant. The results showed that age, nodule number, BMI and serum TSH were the related factors for DTC. More aggressive behaviors of DTC were observed in male patients, and more attention should be focused on the timely diagnosis and treatment of these patients.

Malignant insulinoma: Report of 6 patients and literature review.

OBJECTIVE: Patients with malignant insulinoma always present with symptoms of severe hypoglycemia and have poor life expectancy. In addition, inoperable metastatic malignant insulinomas are very difficult to manage. The aim of this report is to present our successful experiences in diagnosis and treatment of this disease in 6 patients. PATIENTS/METHODS: Six patients (male 2, female 4) with malignant insulinomas were admitted into our hospital. Their clinical histories, including clinical presentations, endocrine evaluations, radiological images, pathological examination and treatments, were reviewed. RESULTS: The diagnosis of malignant insulinoma combined with liver metastases was confirmed in all patients by endocrine evaluation and radiological images. Patients 1-3 underwent surgical management. The primary and metastasized tumors were completely resected. After successful surgery, no hypoglycemia recurred. Patients 4-6 did not undergo surgery because of systemic disease and poor health. Instead, they were administrated with diazoxide 50 mg Three Times a Day (TID), with final doses up to 200-300 mg TID. These 3 patients had good responses to diazoxide administration. After treatment, the frequency and severity of hypoglycemia were improved significantly. All 6 patients had better life quality than previously expected. CONCLUSION: Combination of surgical and medical approaches can improve life quality and prolong survival of patients with malignant insulinomas.

Rare and curable renin-mediated hypertension: a series of six cases and a literature review.

BACKGROUND: Reninoma is an extremely rare renal tumor characterized by excessive renin secretion causing secondary hypertension and hypokalemia. Reninoma is a benign and highly manageable lesion if it is discovered early and removed surgically. METHODS: We report six cases of reninoma and provide a literature review on this rare disease, highlighting the diagnostic evaluation and follow-up of each patient. RESULTS AND CONCLUSIONS: Reninoma should be considered in young adults with elevated renin activity and refractory hypertension. Imaging studies and selective venous catheterization are often helpful in identifying the lesion. In most cases of reninoma presenting with renin-mediated hypertension, conservative surgical treatment should be considered to remove the small, superficial lesion.

Mutation analyses in pedigrees and sporadic cases of ethnic Han Chinese Kallmann syndrome patients.

Kallmann syndrome, a form of idiopathic hypogonadotropic hypogonadism, is characterized by developmental abnormalities of the reproductive system and abnormal olfaction. Despite association of certain genes with idiopathic hypogonadotropic hypogonadism, the genetic inheritance and expression are complex and incompletely known. In the present study, seven Kallmann syndrome pedigrees in an ethnic Han Chinese population were screened for genetic mutations. The exons and intron-exon boundaries of 19 idiopathic hypogonadotropic hypogonadism (idiopathic hypogonadotropic hypogonadism)-related genes in seven Chinese Kallmann syndrome pedigrees were sequenced. Detected mutations were also tested in 70 sporadic Kallmann syndrome cases and 200 Chinese healthy controls. In pedigrees 1, 2, and 7, the secondary sex characteristics were poorly developed and the patients' sense of smell was severely or completely lost. We detected a genetic mutation in five of the seven pedigrees: homozygous KAL1 p.R191ter (pedigree 1); homozygous KAL1 p.C13ter (pedigree 2; a novel mutation); heterozygous FGFR1 p.R250W (pedigree 3); and homozygous PROKR2 p.Y113H (pedigrees 4 and 5). No genetic change of the assayed genes was detected in pedigrees 6 and 7. Among the 70 sporadic cases, we detected one homozygous and one heterozygous PROKR2 p.Y113H mutation. This mutation was also detected heterozygously in 2/200 normal controls and its pathogenicity is likely questionable. The genetics and genotype-phenotype relationships in Kallmann syndrome are complicated. Classical monogenic inheritance does not explain the full range of genetic inheritance of Kallmann syndrome patients. Because of stochastic nature of genetic mutations, exome analyses of Kallmann syndrome patients may provide novel insights.

Characterization of papillary thyroid microcarcinomas using sonographic features in malignant papillary thyroid cancer: a retrospective analysis.

The diagnosis of malignant thyroid nodules is still a clinical challenge. This study aimed to determine the ultrasonographic characteristics of papillary thyroid carcinoma. The ultrasonographic and pathological data of 2453 thyroid nodules in a cohort of 1895 Chinese patients who underwent thyroidectomy from January 2010 to December 2012 were retrospectively reviewed. Anteroposterior and transversal (AP/TR) diameters ≥1, solid structure, infiltrative margins, hypoechoic appearance, and microcalcifications were more common in malignant nodules than in benign nodules (P < 0.01). These ultrasonographic features were independent risk factors of malignancy (P < 0.01) as determined by logistic regression analysis. Based on multivariate analysis, these characteristics were also present in large nodules (diameter >10 mm). However, in small nodules (diameter ≤10 mm), only AP/TR ≥1 and infiltrative margins were independent risk factors of malignancy (P < 0.01). Ultrasonography is of high diagnostic value for malignant thyroid nodules and may help to improve the differential diagnosis. Small and large nodules have distinct ultrasonographic features.

Acquired generalized lipodystrophy in a young lean Chinese girl. Case Report.

Lipodystrophies is a really rare group of diseases characterized by altered body fat amount and/or repartition and serious insulin resistance.We reported a lean Chinese girl with acquired generalized lipodystrophy, who had a long history of poorly controlled diabetes mellitus (DM) despite with extremely high dose insulin (6 u/kg/d) therapy, combined with severe hypertriglyceridemia and acanthosis nigricans. The differential diagnosis of Lipodystrophies should be considered in lean patients presenting with early onset DM, combined with serious insulin resistance.

Female sex hormones are associated with the reduction of serum sodium and hypertension complications in patients with aldosterone-producing adenoma.

This study was conducted to evaluate gender-related differences in clinical characteristics and vascular complications in patients with aldosterone-producing adenomas (APA). Clinical characteristics, biochemical markers and incidence of vascular complications were compared by gender in 187 consecutive patients with APA confirmed by pathological diagnosis. Patients were separated into two groups based on ages either older or younger than 49 years, the average age of menopause among Chinese women (<49 y and ≥49 y). Males had significantly higher BMI than females in the age group of <49 years (p = 0.017). In the <49 years group, males had significantly higher serum sodium levels (p = 0.003). However, no such gender differences in clinical characteristics were observed in patients ≥49 years. A higher proportion of vascular complications was observed in males as compared to females aged <49 years but the difference was not statistically significant (51.4% vs. 34.8%, p = 0.105). The only gender difference observed in vascular complications between patients aged ≥49 years was that a significantly greater proportion of males had cerebrovascular complication compared to females (p = 0.006). Our data suggest that female sex hormones are implicated in reducing serum sodium concentration and vascular complications in female APA patients.

[The clinical characteristics of multi-detector computed tomography of congenital adrenal hyperplasia].

OBJECTIVE: To explore the imaging features of congenital adrenal cortex hyperplasia (CAH). METHODS: A total of 45 patients clinically confirmed as CAH were retrospectively analyzed to investigate the imaging features and strengthening way of the multi-detector-row Computed tomography. RESULTS: The imaging features of all the cases presented as following: 25 with bilateral adrenal hyperplasia, 6 with unilateral adrenal hyperplasia, 6 with adrenal nodular hyperplasia, 2 with adrenal hyperplasia and unilateral solid cystic lesion, 2 with adrenal hyperplasia and double side real cystic lesion, 1 with adrenal hyperplasia and unilateral cystic changes and 3 with normal adrenal. The unilateral or bilateral hyperplasia adrenal could be homogeneously enhanced, while the enhanced performance of other cases was inequitable. CONCLUSIONS: The adrenal imaging features of CAH by multi-detector-row CT are variable, with the bilateral adrenal hyperplasia as the main form, which could be restored to normal morphology after hormone replacement therapy.No regression of the tumor size is observed in cases with adrenal mass. CT scanning combined with clinical manifestation and biochemical examination could facilitate the diagnosis of CAH.

Pituitary stalk interruption syndrome in 58 Chinese patients: clinical features and genetic analysis.

OBJECTIVES: Pituitary stalk interruption syndrome (PSIS) is rare and its clinical features and pathogenesis are poorly understood. This study characterized the clinical and genetic features of PSIS in Chinese patients. DESIGN AND PATIENTS: Clinical data of 58 patients with PSIS and 46 patients with GH deficiency but a normal pituitary stalk (NPS) were retrospectively analysed. HESX1, LHX4, OTX2 and SOX3 polymorphisms were screened in 33 PSIS patients, and GH1 and GHRHR in 4 NPS patients. RESULTS: Deficiency of GH was 100% in both PSIS and NPS groups. Other deficiency rates for PSIS and NPS groups were as follows: ACTH, 77·6% and 23·9%; TSH, 43·1% and 10·9%; LH/FSH, 94·2% and 47·4%; and combined pituitary hormone, 93·1% and 41·3% respectively. In PSIS and NPS patients, the percentages of anterior pituitary hypoplasia were 98·3% and 54·3%, pituitary stalk abnormality were 100% and 0%, and ectopic neurohypophysis were 91·4% and 0%. A novel heterozygous sequence variant (c.142A>T, p.T48S) was found in HESX1 in one PSIS patient, 3 polymorphisms (c.63T>C, p.G21G; c.450C>T, p.N150N; and c.983A>G, p.N328S) in LHX4 in 7, 1 and 31 PSIS patients, respectively, and a hemizygous polymorphism (c.157G>C, p.V53L) in SOX3 in one PSIS patient. No OTX2 abnormality was detected in PSIS patients, and no GH1 or GHRHR polymorphisms in NPS patients. CONCLUSIONS: Compared with NPS, PSIS patients had more severe anterior pituitary hormone deficiency, lower anterior pituitary hormone secretion and higher probability of abnormal pituitary morphology. HESX1, LHX4 and SOX3 polymorphisms may be associated with PSIS.

Clinical and genetic analysis of three Chinese patients with steroid 5α-reductase type 2 deficiency.

Steroid 5α-reductase type 2 deficiency (5α-RD2) is a rare autosomal recessive inherited disorder caused by mutations in the SRD5A2 gene. Its clinical features and pathogenesis in Chinese patients are poorly understood. This study aimed to characterize the clinical features and genetically analyze the SRD5A2 gene in three Chinese 5α-RD2 patients. The patients were characterized by ambiguous genitalia and spontaneous virilization without breast development at puberty. Elevated post-human chorionic gonadotropin stimulation T/DHT ratios were useful indicators of 5α-RD2 (with ratios of 20.4, 20.1, and 26.6 in the three patients, respectively). Two compound heterozygous mutations in the SRD5A2 gene were identified: p.G203S/p.R246Q in patients 1 and 2 and p.G203S/c.655delT in patient 3. The father and the mother of patients 1 and\xa02 were carriers of p.R246Q and p.G203S, respectively. p.G203S appears to be common in Chinese 5α-RD2 patients. Early genetic analysis should be performed in suspected patients to improve prognosis.

[LRP16 gene causes insulin resistance in C2-C12 cells by inhibiting the IRS-1 signaling and the transcriptional activity of peroxisome proliferator actived receptor γ].

OBJECTIVE: To explore the effect of LRP (leukemia related protein) 16 on insulin resistance in C2-C12 cells and explore its molecular mechanism. METHODS: Lipidosome transfection and lentivirus mediated siRNA (small interfering RNA) technology were used to establish LRP 16 overexpression and underexpression cell lines and their corresponding control cell lines. And 2-deoxy-[(3)H]-glucose was used to measure the effect of LRP 16 on insulin-stimulated glucose uptake. The effects of LRP16 on the phosphorylation of IRS (insulin receptor substrate)-1, Akt and the expressions of PI3K (p85), PPAR (peroxisome proliferator actived receptor) γ and GLUT-4 were detected by Western blot. Luciferase was used to study the effect of LRP16 on the transcriptional activity of PPARγ. RESULTS: Insulin-stimulated glucose uptake decreased to 46% of the control when LRP16 was over-expressed [(4700 ± 97) vs. (10200 ± 347), P < 0.01]. And the insulin-stimulated glucose uptake was 1.73 fold of control when the expression of LRP16 was suppressed in C2-C12 cells [(17600 ± 466) vs (10200 ± 91), P < 0.05]. The overexpression of LRP16 attenuated the insulin-induced tyrosine phosphorylation of IRS-1, the phosphorylation of Akt and the expressions of PI3K (p85), PPARγ and GLUT-4. But it promoted the insulin-induced phosphorylation of IRS-1 at Ser307 in C2-C12 cells. LRP16 decreased the transcriptional activity of PPARγ in a dose-dependent manner. The transcriptional activity of PPARγ decreased to 43% and 27% of the control when the doses of pcDNA3.1-16 were 0.4 µg and 0.5 µg [(76 ± 11) vs (33 ± 9), P < 0.01] and 27% [(21 ± 9) vs (76 ± 11), P < 0.01]. CONCLUSION: LRP16 gene causes insulin resistance in C2-C12 cells by inhibiting the IRS-1 signaling and the transcriptional activity of PPARγ.