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Toronto Notes 2019
Male Reproductive Endocrinology
Endocrinology E45
Differential Diagnosis
• primarybonelesions
■ osteogenic sarcoma ■ multiple myeloma ■ fibrous dysplasia
• secondarybonelesions
■ osteitis fibrosa cystica ■ metastases
Clinical Features
• usuallyasymptomatic(routinex-rayfindingorelevatedALP)
• severebonepain(e.g.pelvis,femur,tibia)isoftenthepresentingcomplaint • skeletaldeformities:bowedtibias,kyphosis,frequentfractures
• skullinvolvement:headaches,increasedhatsize,deafness
• increasedwarmthoverinvolvedbonesduetoincreasedvascularity
• highoutputCHF
• hypercalcemiawithimmobilization
• osteosarcoma
Investigations
• laboratory
■  serum ALP (unless burnt out), Ca2+ normal or , PO43- normal
■ elevated CTX (bone resorption marker, breakdown product of collagen in the blood)
• imaging
■ confirmation on x-ray required for diagnosis
■ bone scan to evaluate the extent of disease and identify asymptomatic sites
■ skeletal survey: involved bones are denser and expanded with cortical thickening
◆ initial lesion may be destructive and radiolucent ◆ multiple fissure fractures in long bones
Complications
• local
■ fractures; osteoarthritis
■ cranial nerve compression and palsies (e.g. deafness), spinal cord compression ■ osteosarcoma/sarcomatous change in 1-3%
◆ indicated by marked bone pain, new lytic lesions and suddenly increased ALP • systemic
■ hypercalcemia and nephrolithiasis
■ high output CHF due to increased vascularity
Treatment
• goals:decreasepain,decreaserateofremodelling
• weight-bearingexercise
• adequatecalciumandvitaminDintaketopreventdevelopmentofsecondaryhyperparathyroidism • treat medically if symptomatic or asymptomatic with ALP >3x normal or planned surgery
■ bisphosphonates, e.g. zoledronic acid 5 mg IV per yr (preferred) OR alendronate 40 mg PO OD x 6 moORrisedronate30mgPOODx3mo
■ calcitonin 50-100 U/d SC if unable to tolerate bisphosphonate • surgeryforfractures,deformity,degenerativechanges
Male Reproductive Endocrinology
Androgen Regulation
• testosterone(fromLeydigcells)primarilyinvolvedinnegativefeedbackonLHandGnRH,whereas inhibin (from Sertoli cells) suppresses FSH secretion
Tests of Testicular Function
• testicularsize(lowerlimit=4cmx2.5cminadult).Canuseorchidometertomeasuretesticular volume (12-25 ml = adult size)
• LH,FSH,total,bioavailable,and/orfreetestosterone
• humanchorionicgonadotropin(hCG)stimulationtest
■ assesses ability of Leydig cell to respond to gonadotropin • semenanalysis
■ semen volume, sperm concentration, morphology, and motility are the most commonly used parameters
• testicularbiopsy
■ indicated with normal FSH and azoospermia/oligospermia
Hypothalamus
Anterior Pituitary
GnRH
Pulses
LH
Sertoli
Cell Cell
Testosterone
FSH
Inhibin
Testes
Leydig
Figure 20. Hypothalamo-pituitary-gonadal axis