HOSP #	Mr JB	WARD	Endocrine Department – CathLab – UCT private Hospital
CONSULTANT	Dr Jody Rusch	DOB/AGE	53y Male

Abnormal Result

Upon authorizing blood results I came across a aldosterone result of 23300 pmol/L.

After a moment of brief anxiety, luckily I realized this was part of a series of tests performed by my colleagues in the Department.

Presenting Complaint

Medical complaint: Suspected Conn’s disease – right adrenal lesion/ irregular left adrenal gland.

History

The patient was confirmed to have primary hyperaldosteronism.

Unfortunately more information is not known. We were asked to assist with the sampling and the whole history weren’t available.

Examination

Not available

Laboratory Investigations

Other Investigations

Not available for this patient.

Ideally one would need a CT with contrast beforehand to adequately visualize the positions of the adrenal veins, as this may aid in the canulation, especially of the right adrenal vein.

One needs to diagnose hyperaldosteronism (by an appropriate salt loading test) before proceeding to bilateral adrenal vein sampling.

Final Diagnosis

Interpretation

Definition	Formula	Clinical significance
Selectivity index	PCC(side) / PCC (ivc)	>cutoff confirms canulation of adrenal vein >3 stimulated >2 unstimulated
Lateralization index	PAC/PCC (dom) : PAC/PCC (non-dom)	>cutoff confirms laterilization of hyperaldo secretion >4 stimulated >2 unstimulated
Contralateral suppression index (used if inadequate canulation)	PAC/PCC (non-dom) : PAC/PCC (ivc)	<cutoff (<1 or <0.5 – sources differ) indicate ipsilateral suppression and suggest contralateral aldosterone overproduction.

Selectivity index

Right: 1.0 (mean)

Left: 19.0 (mean)

These two results indicate that the left adrenal has been canulated adequately, but the right vein inadequately.

Lateralization index

Unable to comment because of the inadequate canulation of the right adrenal vein. If determined, it would very likely provide a false result.

Contralateral suppression index

1.5 : 1.8 = 0.8

This falls in between some of the referenced cutoffs (<1 and <0.5)

All of the other samples also fall somewhere in this range. Biochemically, these results suggests inadequate right sided venous sampling (a commonly described problem)

Take Home Message

• Procedure is done in the Cath Lab
• The patient received continuous synacthen infusion – as this improves the sensitivity (or perhaps rather specificity) of the test.
• Done under imaging with contrast used for the localisation of the adrenal gland and adrenal vein
• Sequential sampling technique used, generally > 20 mins infusion
• Multi-disciplinary: nurses, anaesthetist, radiographer, intervention radiologists, students, chemical pathologists
• Difficulty with sampling right side for both patients
• Difficulty with interpreting results – most likely due to inadequate canulation of the right adrenal vein

Some important learning points

1. Adrenal vein sampling may be a valuable tool that is underutilised
2. Careful selection of patients essential – also patient should consent to surgical removal of the affected adrenal before this invasive procedure is initiated
3. Inter-disciplinary approach is necessary
4. Obtaining cosyntroponin (aka synacthen) can be difficult (Section 21), but recommended.
5. Right adrenal access difficult: may require specific imaging. Recommended to start on the right or do simulataneous sampling.
6. Adrenalectomy may be curative or help achieve better control of BP thus decrease associated morbidity and mortality in those with unilateral adenoma

HOSP #		WARD	Internal Medicine
CONSULTANT	Dr. Jody Rusch	DOB/AGE	21 y male

Abnormal Result

Potassium of 1.9 mmol/L was found on a blood gas analysis.

Presenting Complaint

Patient presented with a few isolated episodes of muscle weakness. This progressed from 2 weeks before, during the index episode, to become so severe that he couldn’t walk.

History

Patient was given IV potassium + MgSO4 upon which the potassium normalised to 5.5 mmol/L
History of muscle weakness was on and off over the last few months – unable to walk for brief periods of time.
No Family Hx of illnesses / hypokalmeia
No hypertension and no family Hx of hypertension
Patient had sweating more than usual. No other overt Sx of hyperthyroidism.
No medications

The mother had no similar symptoms ever.

The father was unfortunately not involved and not contactable.

Examination

Normal pulses
Small goiter, diffusely enlarger
No cardiovascular system abnormalities

Laboratory Investigations

Potassium upon the current consultation: 4.6 mmol/L
Normal Sodium, Creatinine, calcium, magnesium, phosphate and chloride

Normal pH 7.35
Normal HC03
Suspecting: Hypokalemic periodic paralysis
TSH < 0.01
Free T4: 59 pmol/L
Free T3: 21 pmol/L
TSH-Receptor Antibodies: Increased above the cut-off

Creatine Kinase 749

Other Investigations

The further investigations needed to confirm the diagnosis

Final Diagnosis

Considering the fact that the patient had no renal tubular acidosis, no medication which could cause the low potassium, it was, according to the endocrinologist, likely a diagnosis of Thyrotoxic Periodic Paralysis (TPP).

Patient was placed on Neomercazole and a Beta-adrenergic receptor blocker.

Take Home Message

I wasn’t aware of the condition until this case was brought up to the endocrinology meeting.

Thyrotoxic periodic paralysis is a rare cause of muscle paralysis.

TPP is a disorder most commonly seen in Asian men, is characterized by abrupt onset of hypokalemia and paralysis. The condition primarily affects the lower extremities and is secondary to thyrotoxicosis.

It has been increasingly reported in the USA due to the rise in the immigrant population. Hypokalemia in TPP results from an intracellular shift of potassium induced by the thyroid hormone sensitization of Na⁺/K⁺–ATPase rather than depletion of total body potassium. Treatment of TPP includes prevention of this shift of potassium by using nonselective beta-blockade, correcting the underlying hyperthyroid state, and replacing potassium.

It is important for physicians to distinguish TPP from familial hypokalemic periodic paralysis, a more common cause of periodic paralysis in Caucasians. The absence of a family history of paralysis, male sex, presentation in the second to fourth decades of life, and signs of thyrotoxicosis like sinus tachycardia help in the diagnosis of this disorder. Early recognition of TPP is vital to initiating appropriate treatment and to avoiding the risk of rebound hyperkalemia that may occur if high-dose potassium replacement is given.

It is most common in Asian populations – incidence approximately 2% in patients with thyrotoxicosis of any cause.

It has been recognized in Thais, Filipinos, Vietnamese, Koreans, Malaysians, Hispanics, African Americans, and Caucasians. It is characterized by acute onset of severe hypokalemia and profound proximal muscle weakness in patients with thyrotoxicosis.