Question of the Week - September 2022

 

September 14th, 2022

A 32-year-old woman with no significant PMH is referred to your clinic for an incidental finding of high PTH (325 pg/mL). She does not have any kidney stones, fractured bones, or abdominal, cognitive, or psychiatric symptoms. She does not know if there is any family history of parathyroid cancer. Her calcium level is 10.3 mg/dl, and the remainder of her labs and imaging are all within normal limits. She states that she would prefer to have as little intervention as possible.

Which of the following management options is your next step and why?

A. Parathyroidectomy; her age is an indication for removal of her parathyroid
B. Observe and monitor with serial PTH and ultrasound-guided FNAs; she is clinically asymptomatic
C. Monitor on Vitamin D supplementation only with follow-up in 6 months; she is asymptomatic and would prefer to have minimal intervention
D. Parathyroidectomy; her calcium level is above the normal limit

  • Quiz Answer: Parathyroidectomy; her age is an indication for removal of her parathyroid)

    D is incorrect; normal serum calcium tends to fall between a range of about 8.5-10.5 mg/dl.

    References:

    Wilhelm SM, Wang TS, Ruan DT, et al. The American Association of Endocrine Surgeons Guidelines for Definitive Management of Primary Hyperparathyroidism. JAMA Surg. 2016;151(10):959–968. doi:10.1001/jamasurg.2016.2310 [Article Link]

    https://www.futuremedicine.com/doi/10.2217/ije-2017-0019#_i7

September 28th, 2022

A 15-year-old female presents with mild right-sided hearing loss. She is found to have a 2cm right vestibular schwannoma and a 0.5cm left vestibular schwannoma. This patient most likely has a mutation in which of the following chromosomes?

A. 7
B. 17
C. 22
D. X

  • Quiz Answer: C (22)

    Explanation: Neurofibromatosis type 2 is caused by an autosomal dominant mutation in the NF2 gene on chromosome 22 which encodes the protein merlin. Bilateral schwannomas of the superior vestibular branch of the eighth cranial nerve (vestibular schwannoma or acoustic neuroma) are pathognomonic for NF2. Pendred syndrome is caused by a mutation in pendrin protein encoded by a gene on chromosome 7 (Option B) and can cause deafness. Neurofibromatosis type 1 is caused by a mutation in the neurofibromin tumor suppressor gene located on chromosome 17 (Option C) and is not likely to present with bilateral vestibular schwannomas. Stapes Gusher syndrome is caused by a mutation of the X chromosome (Option D) and can present as deafness with a fixed stapes footplate.

    Reference: Kresak JL, Walsh M. Neurofibromatosis: A Review of NF1, NF2, and Schwannomatosis. J Pediatr Genet. 2016;5(2):98-104. doi:10.1055/s-0036-1579766

 

October 2022