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Endocrine Physiology: Case Studies in Calcium Metabolism. C.W. Spellman PhD, DO Assoc. Prof. Medicine Assist. Dean, Dual Degree Program Head, Endocrinology & Dir. Diabetes Clinics UNTHSC. Normal Values. Ca 8.4 - 10.6 mg/dL PO4 2.5 - 4.5 mg/dL Mg 1.5 - 2.5 mg/dl

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Endocrine Physiology: Case Studies in Calcium Metabolism

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endocrine physiology case studies in calcium metabolism

Endocrine Physiology: Case Studies in Calcium Metabolism

C.W. Spellman PhD, DO

Assoc. Prof. Medicine

Assist. Dean, Dual Degree Program

Head, Endocrinology & Dir. Diabetes Clinics


normal values
Normal Values

Ca 8.4 - 10.6 mg/dL

PO4 2.5 - 4.5 mg/dL

Mg 1.5 - 2.5 mg/dl

Creat 0.6 - 1.3 mg/dL

BUN 8 - 12 mg/dL

Alb 3.5 - 4.5 mg/dL

TSH 0.3 - 5.0 mIU/ml

iPTH 15 - 50 pg/ml

review basic metabolic control of calcium metabolism
Review: Basic Metabolic Control of Calcium Metabolism
  • Low calcium: + PTH
  • High calcium: - PTH
  • PTH: + renal calcium resorption

+ renal phosphate excretion

+ renal 1,25 Vit D3 synthesis

+ calcium resorption from bone

  • Vit D3: + gut absorption of calcium

+ gut absorption of phosphate

signs and symptoms of hypercalcemia
Signs and Symptoms of Hypercalcemia
  • Hypercalcemia may present with vague Si/Sx
  • Si/Sx are quite variable
  • Ill-defined correlation's of symptoms with degree of hypercalcemia
  • Most common presentation: Asymptomatic
  • Calcium ≤12 mg/dL may present with




signs and symptoms of hypercalcemia5
Signs and Symptoms of Hypercalcemia
  • If calcium is > 12 mg/dl, one may see:

Neurol Lethargy, confusion, coma

Psych Depression, psychosis

Cardiol Hypertension

Nephrol DI, nephrolithiasis

GI Nausea/emesis, PUD, anorexia Constipation, pancreatitis

Rheum Proximal weakness, bone loss

causes of hypercalcemia
Causes of Hypercalcemia
  • Differential diagnosis of hypercalcemia

Increased PTH production

Production of PTH-like hormone

Production of Vit D-like factors


Familial disorders

Diseases affecting calcium metabolism

hypercalcemia elevated pth
Hypercalcemia: Elevated PTH
  • Primary elevation of PTH:

85% parathyroid adenoma

10% parathyroid hyperplasia

(3% MEN)

2% parathyroid carcinoma

  • Secondary elevation of PTH

Renal failure

hypercalcemia other causes
Hypercalcemia: Other causes
  • PTH-related peptide (cancers)

Breast, lung, renal


Lymphoma, Leukemia, Myeloma

  • Vit-D3-like factors (granulomatous dz)




hypercalcemia other causes9
Hypercalcemia: Other Causes
  • Drugs





Vit-D intoxication

hypercalcemia other causes10
Hypercalcemia: Other Causes
  • Other diseases



FHH syndrome


signs and symptoms of hypocalcemia
Signs and Symptoms of Hypocalcemia
  • Findings may include:

Neurol Trousseau’s (carpopedal spasm)

Chvostek’s (CN VII spasm)

Paresthesias, tetany

Lethargy, seizures

Respiratory arrest

Cardio Heart block, CHF

Rheum Weakness, cramps

Derm Dry skin, brittle hair

causes of hypocalcemia
Causes of Hypocalcemia
  • PTH absent

a. Hypoparathyroidism (hereditary)

b. Acquired hypoparathyroidism

Surgery (thyroid, parathyroid)

Autoimmune disease

Autoimmune parathyroid destruction

PGA-1, PA, Hashimoto’s, T1DM

Infiltrative disease

Metastatic dz

Alcohol ( PTH release, 20 to  Mg)

causes of hypocalcemia13
Causes of Hypocalcemia
  • PTH absent, cont.


a.  PTH release

b.  PTH responsiveness

  • PTH ineffective

Chronic renal failure

a.  Vit-D 1,25 synthesis

b. PO4 retention

 PTH effects on bone

Vit-D 1,25 synthesis

causes of hypocalcemia14
Causes of Hypocalcemia
  • PTH ineffective, cont.

Dietary Vit-D deficiency

Gut malabsorption of Vit-D

 Sun light exposure


 hepatic degradation of Vit-D

Vit-D resistance


Defective PTH receptor

causes of hypocalcemia15
Causes of Hypocalcemia
  • PTH overwhelmed

Severe, rapid loss of calcium from ECF

a. Acute renal failure

b. Tissue destruction


Tumor lysis


c. “Hungry bone” syndrome

s/p parathyroidectomy

causes of hypocalcemia16
Causes of Hypocalcemia
  • PTH overwhelmed: Mechanisms

a. Acute renal failure, tissue destruction

Decreased renal PO4 excretion

Rapid cellular release of PO4

 Acute hyperphosphatemia

 urinary calcium loss

 Hypocalcemia

b. s/p resection of parathyroid tumor

 Sudden decrease serum PTH

 Rapid bone uptake of calcium

 Hypocalcemia

case 1 new patient with elevated serum calcium
Case 1: New Patient With Elevated Serum Calcium
  • 40 yr male is seen as a new patient to establish care. He has no complaints.
  • PMHx is negative
  • Baseline laboratory studies are significant for serum calcium of 11.5 mg/dL
  • Physical examination is normal
case 1 questions
Case 1, Questions
  • What is the most common cause of asymptomatic hypercalcemia?
  • This patient’s iPTH would be

a. High

b. Normal

c. Low

  • This patient’s PO4 would be

a. High

b. Normal

c. Low

case 2 man with lethargy fatigue and weakness
Case 2: Man With Lethargy, Fatigue and Weakness
  • 60 yr old male presents with complaints of fatigue and weakness over 1 month.
  • PMHx: Negative
  • PE: significant for memory and cognitive defects
  • Lab: Ca 15.0 mg/dL

PO4 2.3 mg/dL

case 2 questions
Case 2, Questions
  • Predict the iPTH values if this patient’s hypercalcemia was due to:

a. Primary hyperparathyroidism

b. Malignancy

c. Vit D intoxication

d. Granulomatous disease

e. Hyperthyroidism

case3 lady with back pain
Case3: Lady With Back Pain
  • 75 yr old lady presents with complaints of low back pain.
  • PMHx: TAH-BSO @ age 35




  • Meds: Verapamil, levothyroxine
case 3 cont
Case 3, cont.
  • PE: Thin, kyphotic
  • Lab: Ca 9.2 mg/dL

BUN/Creat 8/0.9 mg/dL

TSH 2.1 mIU/ml

  • Imaging studies:

CT: Compression fractures T and L spine

DEXA: Loss of bone density

case 3 questions
Case 3, Questions

Which of the following is most likely to be found?

a. Hypophosphatemia

b. Hyperphosphatemia

c. Low Vit D3

d. High Vit D3

e. Low alkaline phosphatase

f. High alkaline phosphatase

g. None of the above

case 4 child with poor school performance
Case 4: Child With Poor School Performance
  • 14 yr old boy is evaluated for poor school performance.
  • PMHx: Unremarkable
  • PE: Lethargic, DTR’s 3+
  • Lab: Ca 5.1 mg/dL

PO4 7.5 mg/dL

Renal function = normal

case 4 questions
Case 4, Questions
  • Possible causes of this patient’s hypocalcemia:


Low calcium intake?


Vit D deficiency?