Transcript 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 UNTHSC
Ca PO4 Mg Creat BUN Alb TSH iPTH Normal Values 8.4 - 10.6 mg/dL 2.5 - 4.5 mg/dL 1.5 - 2.5 mg/dl 0.6 - 1.3 mg/dL 8 - 12 mg/dL 3.5 - 4.5 mg/dL 0.3 - 5.0 mIU/ml 15 - 50 pg/ml
Review: Basic Metabolic Control of Calcium Metabolism
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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
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Hypercalcemia may present with vague Si/Sx Si/Sx are quite variable Ill-defined correlation's of symptoms with degree of hypercalcemia
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Most common presentation: Asymptomatic Calcium ≤12 mg/dL may present with Fatigue Depression Headache
Signs and Symptoms of Hypercalcemia
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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
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Differential diagnosis of hypercalcemia Increased PTH production Production of PTH-like hormone Production of Vit D-like factors Drugs Familial disorders Diseases affecting calcium metabolism
Hypercalcemia: Elevated PTH
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Primary elevation of PTH: 85% parathyroid adenoma 10% parathyroid hyperplasia (3% MEN) 2% parathyroid carcinoma
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Secondary elevation of PTH Renal failure
Hypercalcemia: Other causes
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PTH-related peptide (cancers) Breast, lung, renal Thyroid Lymphoma, Leukemia, Myeloma
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Vit-D3-like factors (granulomatous dz) TB Histoplasmosis Sarcoidosis
Hypercalcemia: Other Causes
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Drugs Lithium Antacids Calcium Thiazides Vit-D intoxication
Hypercalcemia: Other Causes
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Other diseases Hyperthyroidism Paget’s FHH syndrome Immobility
Signs and Symptoms of Hypocalcemia
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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
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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, 2 0 to
Mg)
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Causes of Hypocalcemia PTH absent, cont.
Hypomagnesemia a.
b.
PTH release PTH responsiveness
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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 Hypocalcemia
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PTH ineffective, cont.
Dietary Vit-D deficiency Gut malabsorption of Vit-D
Sun light exposure Anti-convulsants
hepatic degradation of Vit-D Vit-D resistance Pseudohypoparathyroidism Defective PTH receptor
Causes of Hypocalcemia
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PTH overwhelmed Severe, rapid loss of calcium from ECF a. Acute renal failure b. Tissue destruction Rhabdomyolysis Tumor lysis Pancreatitis c. “Hungry bone” syndrome s/p parathyroidectomy
Causes of Hypocalcemia
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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
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40 yr male is seen as a new patient to establish care. He has no complaints.
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PMHx is negative Baseline laboratory studies are significant for serum calcium of 11.5 mg/dL
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Physical examination is normal
Case 1, Questions
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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
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60 yr old male presents with complaints of fatigue and weakness over 1 month.
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PMHx: Negative PE: significant for memory and cognitive defects
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Lab: Ca 15.0 mg/dL PO4 2.3 mg/dL
Case 2, Questions
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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
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75 yr old lady presents with complaints of low back pain.
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PMHx: TAH-BSO @ age 35 Meds: No HRT HTN “Hypothyroid” Verapamil, levothyroxine
Case 3, cont.
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PE: Thin, kyphotic Lab: Ca 9.2 mg/dL BUN/Creat 8/0.9 mg/dL TSH 2.1 mIU/ml
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Imaging studies: CT: Compression fractures T and L spine DEXA: Loss of bone density
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
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14 yr old boy is evaluated for poor school performance.
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PMHx: Unremarkable PE: Lethargic, DTR’s 3+
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Lab: Ca 5.1 mg/dL PO4 7.5 mg/dL Renal function = normal
Case 4, Questions
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Possible causes of this patient’s hypocalcemia: Hypoparathyroidism?
Low calcium intake?
Pseudohypoparathyroidism?
Vit D deficiency?